diff --git a/package-lock.json b/package-lock.json
index c81abf023b62..72ddf4bb83ec 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -34,7 +34,7 @@
                 "@taiga-ui/event-plugins": "4.0.1",
                 "@taiga-ui/prettier-config": "0.113.3",
                 "@taiga-ui/stylelint-config": "0.147.0",
-                "@taiga-ui/tsconfig": "0.113.3",
+                "@taiga-ui/tsconfig": "0.147.10",
                 "@types/glob": "8.1.0",
                 "@types/loader-utils": "2.0.6",
                 "@types/node": "22.5.1",
@@ -9765,9 +9765,9 @@
             "link": true
         },
         "node_modules/@taiga-ui/tsconfig": {
-            "version": "0.113.3",
-            "resolved": "https://registry.npmjs.org/@taiga-ui/tsconfig/-/tsconfig-0.113.3.tgz",
-            "integrity": "sha512-XYQ5VU3Dt4crnI7OZ/BwwMVl7S6c3YUt2+vDWkWv/VLc2yoUu85lEnsl3J5mqasnamENUiSbXWSGxh3h0m2WEA==",
+            "version": "0.147.10",
+            "resolved": "https://registry.npmjs.org/@taiga-ui/tsconfig/-/tsconfig-0.147.10.tgz",
+            "integrity": "sha512-LaNRtPZIwUEPifUwVa4D6H52KJgbEzcb8CeKXvz2hh69ng1GsgrMSQkGm+GtKfuQmlONR8N62R0sIKx0J+jtKQ==",
             "dev": true,
             "license": "Apache-2.0"
         },
diff --git a/package.json b/package.json
index d3c2e3bfd7e2..eb8a79284e8e 100644
--- a/package.json
+++ b/package.json
@@ -130,7 +130,7 @@
         "@taiga-ui/event-plugins": "4.0.1",
         "@taiga-ui/prettier-config": "0.113.3",
         "@taiga-ui/stylelint-config": "0.147.0",
-        "@taiga-ui/tsconfig": "0.113.3",
+        "@taiga-ui/tsconfig": "0.147.10",
         "@types/glob": "8.1.0",
         "@types/loader-utils": "2.0.6",
         "@types/node": "22.5.1",
diff --git a/projects/addon-charts/components/line-chart/line-chart.component.ts b/projects/addon-charts/components/line-chart/line-chart.component.ts
index ace10d3b05f4..a642df97f669 100644
--- a/projects/addon-charts/components/line-chart/line-chart.component.ts
+++ b/projects/addon-charts/components/line-chart/line-chart.component.ts
@@ -48,9 +48,7 @@ export class TuiLineChart {
     private readonly hover$ = new Subject<number>();
     private readonly autoId = tuiInjectId();
 
-    protected readonly hintDirective = inject(TuiLineChartHint, {
-        optional: true,
-    });
+    protected readonly hintDirective = inject(TuiLineChartHint, {optional: true});
 
     protected readonly hintOptions = inject(TuiHintOptionsDirective, {optional: true});
 
@@ -165,8 +163,10 @@ export class TuiLineChart {
 
     protected getImplicit($implicit: TuiPoint): TuiPoint | readonly TuiPoint[] {
         return (
-            this.hintDirective?.getContext(this.value.indexOf($implicit), this) ||
-            $implicit
+            (this.hintDirective?.getContext(
+                this.value.indexOf($implicit),
+                this,
+            ) as readonly TuiPoint[]) ?? $implicit
         );
     }
 
diff --git a/projects/addon-charts/components/line-days-chart/line-days-chart.component.ts b/projects/addon-charts/components/line-days-chart/line-days-chart.component.ts
index 688f11bc0206..ae28ee086ee2 100644
--- a/projects/addon-charts/components/line-days-chart/line-days-chart.component.ts
+++ b/projects/addon-charts/components/line-days-chart/line-days-chart.component.ts
@@ -1,5 +1,5 @@
 import {NgForOf} from '@angular/common';
-import type {AfterViewInit, QueryList} from '@angular/core';
+import {type AfterViewInit, type QueryList} from '@angular/core';
 import {
     ChangeDetectionStrategy,
     Component,
@@ -113,6 +113,12 @@ export class TuiLineDaysChart implements AfterViewInit {
         });
     }
 
+    public get hint():
+        | PolymorpheusContent<TuiContext<[TuiDay, number]>>
+        | PolymorpheusContent<TuiContext<readonly TuiPoint[]>> {
+        return this.hintDirective?.hint ?? this.hintContent;
+    }
+
     public ngAfterViewInit(): void {
         combineLatest([tuiLineChartDrivers(this.charts), this.hovered$])
             .pipe(
@@ -146,6 +152,30 @@ export class TuiLineDaysChart implements AfterViewInit {
         });
     }
 
+    public raise(index: number, {value}: TuiLineChart): void {
+        const x = value[index]?.[0] || 0;
+        const month = this.getDay(x);
+
+        if (!month) {
+            return;
+        }
+
+        if (this.hintDirective) {
+            this.hintDirective.raise(month);
+        } else {
+            this.onHovered(month);
+        }
+    }
+
+    public getContext(index: number, {value}: TuiLineChart): unknown {
+        const x = value[index]?.[0] || 0;
+        const day = this.getDay(x);
+
+        return this.hintDirective && day
+            ? this.hintDirective.getContext(day)
+            : this.getHintContext(x, this.value);
+    }
+
     protected get months(): ReadonlyArray<readonly TuiPoint[]> {
         return this.value.length ? this.breakMonths(this.value) : EMPTY_ARRAY;
     }
@@ -154,18 +184,12 @@ export class TuiLineDaysChart implements AfterViewInit {
         return this.months.length * (this.value[0]?.[0].daysCount || 0);
     }
 
-    protected get hint():
-        | PolymorpheusContent<TuiContext<[TuiDay, number]>>
-        | PolymorpheusContent<TuiContext<readonly TuiPoint[]>> {
-        return this.hintDirective?.hint ?? this.hintContent;
-    }
-
     @tuiPure
     protected getHintContext(
         x: number,
         value: ReadonlyArray<[TuiDay, number]>,
-    ): [TuiDay, number] {
-        return value[x - (value[0]?.[0]?.day || 0) + 1];
+    ): [TuiDay, number] | null {
+        return value[x - (value[0]?.[0]?.day || 0) + 1] ?? null;
     }
 
     protected readonly daysStringify: TuiStringHandler<number> = (index) => {
@@ -183,34 +207,10 @@ export class TuiLineDaysChart implements AfterViewInit {
         return index - offset;
     }
 
-    protected raise(index: number, {value}: TuiLineChart): void {
-        const x = value[index]?.[0] || 0;
-        const month = this.getDay(x);
-
-        if (!month) {
-            return;
-        }
-
-        if (this.hintDirective) {
-            this.hintDirective.raise(month);
-        } else {
-            this.onHovered(month);
-        }
-    }
-
     protected getWidth(index: number): number {
         return (this.getDay(index)?.daysCount || 0) * this.months.length;
     }
 
-    protected getContext(index: number, {value}: TuiLineChart): unknown {
-        const x = value[index]?.[0] || 0;
-        const day = this.getDay(x);
-
-        return this.hintDirective && day
-            ? this.hintDirective.getContext(day)
-            : this.getHintContext(x, this.value);
-    }
-
     @tuiPure
     private breakMonths(
         value: ReadonlyArray<[TuiDay, number]>,
diff --git a/projects/addon-charts/components/line-days-chart/line-days-chart.template.html b/projects/addon-charts/components/line-days-chart/line-days-chart.template.html
index 0d981259f6dc..0010f61862dc 100644
--- a/projects/addon-charts/components/line-days-chart/line-days-chart.template.html
+++ b/projects/addon-charts/components/line-days-chart/line-days-chart.template.html
@@ -7,8 +7,8 @@
     [style.zIndex]="zIndex"
     [tuiHintContent]="hintContent ? hint : ''"
     [value]="month"
-    [width]="first ? firstWidth : getWidth(month[0][0])"
-    [x]="first ? 0 : getX(month[0][0])"
+    [width]="first ? firstWidth : getWidth(month[0]?.[0] ?? 0)"
+    [x]="first ? 0 : getX(month[0]?.[0] ?? 0)"
     [xStringify]="xStringify ? daysStringify : null"
     [y]="y"
     [yStringify]="yStringify"
diff --git a/projects/addon-charts/components/pie-chart/pie-chart.template.html b/projects/addon-charts/components/pie-chart/pie-chart.template.html
index be29eecbd2d3..9e4c9c6682ab 100644
--- a/projects/addon-charts/components/pie-chart/pie-chart.template.html
+++ b/projects/addon-charts/components/pie-chart/pie-chart.template.html
@@ -40,7 +40,7 @@
             [style.color]="'var(--tui-chart-categorical-0' + index + ')'"
             [tuiHint]="hintContent"
             [tuiHintContext]="{$implicit: index}"
-            [tuiPieChart]="segments[index]"
+            [tuiPieChart]="segments[index] || [0, 0]"
             (tuiHoveredChange)="onHovered($event, index)"
         />
     </g>
diff --git a/projects/cdk/directives/repeat-times/test/repeat-times.directive.spec.ts b/projects/cdk/directives/repeat-times/test/repeat-times.directive.spec.ts
index a833f8f8d97d..b60a6b7d5582 100644
--- a/projects/cdk/directives/repeat-times/test/repeat-times.directive.spec.ts
+++ b/projects/cdk/directives/repeat-times/test/repeat-times.directive.spec.ts
@@ -82,9 +82,9 @@ describe('TuiRepeatTimes directive', () => {
         });
 
         it('passes index as implicit context', () => {
-            expect(debugElements[0].nativeElement.title).toBe('0');
-            expect(debugElements[1].nativeElement.title).toBe('1');
-            expect(debugElements[2].nativeElement.title).toBe('2');
+            expect(debugElements[0]?.nativeElement.title).toBe('0');
+            expect(debugElements[1]?.nativeElement.title).toBe('1');
+            expect(debugElements[2]?.nativeElement.title).toBe('2');
         });
     });
 });
diff --git a/projects/cdk/utils/dom/test/get-element-obscurers.spec.ts b/projects/cdk/utils/dom/test/get-element-obscurers.spec.ts
index 5d2f4d3490e3..cfc096149674 100644
--- a/projects/cdk/utils/dom/test/get-element-obscurers.spec.ts
+++ b/projects/cdk/utils/dom/test/get-element-obscurers.spec.ts
@@ -105,9 +105,9 @@ describe('tuiGetElementObscures', () => {
             const mockElementFromPoint = jest.mocked(ownerDocument.elementFromPoint);
 
             mockElementFromPoint
-                .mockReturnValueOnce(others[0])
-                .mockReturnValueOnce(others[1])
-                .mockReturnValueOnce(others[2])
+                .mockReturnValueOnce(others[0]!)
+                .mockReturnValueOnce(others[1]!)
+                .mockReturnValueOnce(others[2]!)
                 .mockReturnValueOnce(element);
 
             expect(tuiGetElementObscures(element)).toBeNull();
diff --git a/projects/core/components/calendar/test/calendar-sheet.component.spec.ts b/projects/core/components/calendar/test/calendar-sheet.component.spec.ts
index 7d7faeaf2948..94b8a57c4d0a 100644
--- a/projects/core/components/calendar/test/calendar-sheet.component.spec.ts
+++ b/projects/core/components/calendar/test/calendar-sheet.component.spec.ts
@@ -103,12 +103,12 @@ describe('CalendarSheet', () => {
                 it('blocked date under condition', () => {
                     expect(getDisabledCalendarItems().length).toBe(1);
                     expect(
-                        getDisabledCalendarItems()[0].nativeElement.textContent.trim(),
+                        getDisabledCalendarItems()[0]?.nativeElement.textContent.trim(),
                     ).toBe('20');
                 });
 
                 it('click on blocked date does not change value', () => {
-                    getDisabledCalendarItems()[0].nativeElement.click();
+                    getDisabledCalendarItems()[0]?.nativeElement.click();
                     fixture.detectChanges();
 
                     expect(testComponent.value).toBeNull();
diff --git a/projects/demo-playwright/tests/deep/deep-select.spec.ts b/projects/demo-playwright/tests/deep/deep-select.spec.ts
index 84b7e8c0d21e..7be8bdf53b2e 100644
--- a/projects/demo-playwright/tests/deep/deep-select.spec.ts
+++ b/projects/demo-playwright/tests/deep/deep-select.spec.ts
@@ -57,7 +57,7 @@ test.describe('Deep / Select', () => {
                 if (cleaner) {
                     await cleaner.click();
                 } else {
-                    await options[0].focus();
+                    await options[0]?.focus();
                     await page.keyboard.down('Enter');
                 }
 
diff --git a/projects/demo-playwright/tests/kit/slider/slider.spec.ts b/projects/demo-playwright/tests/kit/slider/slider.spec.ts
index f1f876dae8cf..bc15472cbd8c 100644
--- a/projects/demo-playwright/tests/kit/slider/slider.spec.ts
+++ b/projects/demo-playwright/tests/kit/slider/slider.spec.ts
@@ -162,7 +162,7 @@ test.describe('Slider', () => {
             });
 
             test('=> 0', async () => {
-                await tickLabels[0].click();
+                await tickLabels[0]?.click();
 
                 await expect(async () => {
                     expect(await slider.value).toBe(0);
@@ -173,7 +173,7 @@ test.describe('Slider', () => {
             });
 
             test('=> 500', async () => {
-                await tickLabels[2].click();
+                await tickLabels[2]?.click();
 
                 await expect(async () => {
                     expect(await slider.value).toBe(500);
@@ -184,7 +184,7 @@ test.describe('Slider', () => {
             });
 
             test('=> 750', async () => {
-                await tickLabels[3].click();
+                await tickLabels[3]?.click();
 
                 await expect(async () => {
                     expect(await slider.value).toBe(750);
@@ -195,7 +195,7 @@ test.describe('Slider', () => {
             });
 
             test('=> 1000', async () => {
-                await tickLabels.at(-1)!.click();
+                await tickLabels.at(-1)?.click();
 
                 await expect(async () => {
                     expect(await slider.value).toBe(1000);
diff --git a/projects/demo-playwright/utils/page-objects/calendar-range.po.ts b/projects/demo-playwright/utils/page-objects/calendar-range.po.ts
index 2880d0e8642d..ed0fbe636942 100644
--- a/projects/demo-playwright/utils/page-objects/calendar-range.po.ts
+++ b/projects/demo-playwright/utils/page-objects/calendar-range.po.ts
@@ -14,14 +14,14 @@ export class TuiCalendarRangePO {
     public async selectItem(index: number): Promise<void> {
         const items = await this.getItems();
 
-        await items[index].click();
+        await items[index]?.click();
     }
 
     public async itemHasCheckmark(index: number): Promise<boolean> {
         const items = await this.getItems();
 
         const itemCheckmark = await items[index]
-            .locator('[automation-id="tui-calendar-range__checkmark"]')
+            ?.locator('[automation-id="tui-calendar-range__checkmark"]')
             .count();
 
         return !!itemCheckmark;
diff --git a/projects/demo-playwright/utils/page-objects/input-date-range.po.ts b/projects/demo-playwright/utils/page-objects/input-date-range.po.ts
index bb724c0aceee..3ec9104de43e 100644
--- a/projects/demo-playwright/utils/page-objects/input-date-range.po.ts
+++ b/projects/demo-playwright/utils/page-objects/input-date-range.po.ts
@@ -26,14 +26,14 @@ export class TuiInputDateRangePO {
     public async selectItem(index: number): Promise<void> {
         const items = await this.getItems();
 
-        await items[index].click();
+        await items[index]?.click();
     }
 
     public async itemHasCheckmark(index: number): Promise<boolean> {
         const items = await this.getItems();
 
         const itemCheckmark = await items[index]
-            .locator('[automation-id="tui-calendar-range__checkmark"]')
+            ?.locator('[automation-id="tui-calendar-range__checkmark"]')
             .count();
 
         return !!itemCheckmark;
diff --git a/projects/demo-playwright/utils/page-objects/textfield-with-data-list.po.ts b/projects/demo-playwright/utils/page-objects/textfield-with-data-list.po.ts
index 031fd1ebb81e..c91b61085168 100644
--- a/projects/demo-playwright/utils/page-objects/textfield-with-data-list.po.ts
+++ b/projects/demo-playwright/utils/page-objects/textfield-with-data-list.po.ts
@@ -17,7 +17,7 @@ export class TuiTextfieldWithDataListPO {
         const options = await this.getOptions();
 
         for (const optionIndex of indexes) {
-            await options[optionIndex].click();
+            await options[optionIndex]?.click();
         }
     }
 
diff --git a/projects/demo/src/modules/app/app.config.ts b/projects/demo/src/modules/app/app.config.ts
index 32b22763230a..c654cbcf1966 100644
--- a/projects/demo/src/modules/app/app.config.ts
+++ b/projects/demo/src/modules/app/app.config.ts
@@ -104,7 +104,7 @@ export const config: ApplicationConfig = {
                 }
 
                 return `${link}/${pkg.toLowerCase()}/${type.toLowerCase()}/${(
-                    header[0].toLowerCase() + header.slice(1)
+                    (header[0]?.toLowerCase() ?? '') + header.slice(1)
                 ).replaceAll(/[A-Z]/g, (m) => `-${m.toLowerCase()}`)}`;
             },
         },
diff --git a/projects/demo/src/modules/app/landing/index.html b/projects/demo/src/modules/app/landing/index.html
index d8f00a257cad..c4e26437b90b 100644
--- a/projects/demo/src/modules/app/landing/index.html
+++ b/projects/demo/src/modules/app/landing/index.html
@@ -21,7 +21,7 @@
     </div>
     <div
         class="container"
-        (waIntersectionObservee)="intersected = $event[0].isIntersecting || intersected"
+        (waIntersectionObservee)="intersected = $event[0]?.isIntersecting || intersected"
     >
         <iframe
             *ngIf="intersected || current === 1"
@@ -160,7 +160,7 @@ <h2 class="opensource">It’s open source</h2>
     waIntersectionObserver
     waIntersectionThreshold="0.5"
     class="screen"
-    (waIntersectionObservee)="onIntersection($event, index)"
+    (waIntersectionObservee)="$event[0] && onIntersection($event[0], index)"
 ></div>
 
 <footer class="footer">
diff --git a/projects/demo/src/modules/app/landing/index.ts b/projects/demo/src/modules/app/landing/index.ts
index f403c0c9a2a4..39850a88b8b8 100644
--- a/projects/demo/src/modules/app/landing/index.ts
+++ b/projects/demo/src/modules/app/landing/index.ts
@@ -64,7 +64,7 @@ export default class Page implements OnInit {
     }
 
     protected onIntersection(
-        [{isIntersecting, target}]: IntersectionObserverEntry[],
+        {isIntersecting, target}: IntersectionObserverEntry,
         index: number,
     ): void {
         if (isIntersecting) {
diff --git a/projects/demo/src/modules/app/stackblitz/stackblitz-resources-loader.ts b/projects/demo/src/modules/app/stackblitz/stackblitz-resources-loader.ts
index 21ed635a34fc..dab9a917fd2f 100644
--- a/projects/demo/src/modules/app/stackblitz/stackblitz-resources-loader.ts
+++ b/projects/demo/src/modules/app/stackblitz/stackblitz-resources-loader.ts
@@ -20,10 +20,11 @@ export abstract class AbstractTuiStackblitzResourcesLoader {
                 ].map(tuiRawLoad),
             );
 
-        const [angularJson, tsconfig] = tuiTryParseMarkdownCodeBlock(configsContent);
-        const [mainTs] = tuiTryParseMarkdownCodeBlock(mainTsContent);
-        const [indexHtml] = tuiTryParseMarkdownCodeBlock(indexHtmlContent);
-        const [globalStyles] = tuiTryParseMarkdownCodeBlock(stylesContent);
+        const [angularJson = '', tsconfig = ''] =
+            tuiTryParseMarkdownCodeBlock(configsContent);
+        const [mainTs = ''] = tuiTryParseMarkdownCodeBlock(mainTsContent);
+        const [indexHtml = ''] = tuiTryParseMarkdownCodeBlock(indexHtmlContent);
+        const [globalStyles = ''] = tuiTryParseMarkdownCodeBlock(stylesContent);
 
         return {angularJson, tsconfig, mainTs, indexHtml, globalStyles};
     }
diff --git a/projects/demo/src/modules/app/stackblitz/starter/index.ts b/projects/demo/src/modules/app/stackblitz/starter/index.ts
index a3f1da6c93ca..b4c59f03b43d 100644
--- a/projects/demo/src/modules/app/stackblitz/starter/index.ts
+++ b/projects/demo/src/modules/app/stackblitz/starter/index.ts
@@ -40,8 +40,8 @@ export default class Page implements OnInit {
                 description:
                     'A starter with Taiga UI library\nDocumentation: https://taiga-ui.dev',
                 files: {
-                    [appPrefix`app.template.html`]: appTemplate,
-                    [appPrefix`app.component.ts`]: appComponent,
+                    [appPrefix`app.template.html`]: appTemplate ?? '',
+                    [appPrefix`app.component.ts`]: appComponent ?? '',
                     [appPrefix`app.style.less`]:
                         "@import '@taiga-ui/core/styles/taiga-ui-local.less';",
                 },
diff --git a/projects/demo/src/modules/components/abstract/control.ts b/projects/demo/src/modules/components/abstract/control.ts
index fd01b85b84a5..05de9467dae8 100644
--- a/projects/demo/src/modules/components/abstract/control.ts
+++ b/projects/demo/src/modules/components/abstract/control.ts
@@ -63,11 +63,11 @@ export abstract class AbstractExampleTuiControl
 
     public customContentSelected = this.customContentVariants[0];
 
-    public inputMode = this.inputModeVariants[0];
+    public inputMode = this.inputModeVariants[0]!;
 
     public maxLength: TuiPossibleGenericType | null = null;
 
-    public type = this.typeVariants[0];
+    public type = this.typeVariants[0]!;
 
     public cleaner = false;
 
@@ -79,7 +79,7 @@ export abstract class AbstractExampleTuiControl
 
     public labelOutside = false;
 
-    public size: TuiSizeL | TuiSizeS = this.sizeVariants[2];
+    public size: TuiSizeL | TuiSizeS = this.sizeVariants[2]!;
 
     public exampleText = '';
 
@@ -87,13 +87,13 @@ export abstract class AbstractExampleTuiControl
 
     public readonly iconLeftVariants = ['', '@tui.mail', '@tui.pie-chart'];
 
-    public iconStart = this.iconLeftVariants[0];
+    public iconStart = this.iconLeftVariants[0]!;
 
-    public hintContent = this.hintContentVariants[0];
+    public hintContent = this.hintContentVariants[0]!;
 
-    public hintDirection = this.hintDirectionVariants[0];
+    public hintDirection = this.hintDirectionVariants[0]!;
 
-    public hintAppearance = this.hintAppearanceVariants[0];
+    public hintAppearance = this.hintAppearanceVariants[0]!;
 
     public dropdownOpen = new BehaviorSubject(false);
 
@@ -111,7 +111,7 @@ export abstract class AbstractExampleTuiControl
         'auto',
     ];
 
-    public dropdownLimitWidth = this.dropdownLimitWidthVariants[0];
+    public dropdownLimitWidth = this.dropdownLimitWidthVariants[0]!;
 
     public readonly dropdownDirectionVariants: readonly TuiVerticalDirection[] = [
         'bottom',
@@ -132,9 +132,9 @@ export abstract class AbstractExampleTuiControl
         'Very long text',
     ];
 
-    public prefix = this.prefixVariants[0];
+    public prefix = this.prefixVariants[0]!;
 
-    public postfix = this.prefixVariants[0];
+    public postfix = this.prefixVariants[0]!;
 
     public dropdownOffset = TUI_DROPDOWN_DEFAULT_OPTIONS.offset;
 
diff --git a/projects/demo/src/modules/components/abstract/hint.ts b/projects/demo/src/modules/components/abstract/hint.ts
index 3da46415367b..adc2debda777 100644
--- a/projects/demo/src/modules/components/abstract/hint.ts
+++ b/projects/demo/src/modules/components/abstract/hint.ts
@@ -3,9 +3,9 @@ import {TUI_HINT_DIRECTIONS} from '@taiga-ui/core';
 export abstract class AbstractExampleTuiHint {
     public readonly appearanceVariants = ['', 'error', 'dark'];
 
-    public appearance = this.appearanceVariants[0];
+    public appearance = this.appearanceVariants[0]!;
 
     public readonly directionVariants = TUI_HINT_DIRECTIONS;
 
-    public direction = this.directionVariants[0];
+    public direction = this.directionVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/abstract/interactive.ts b/projects/demo/src/modules/components/abstract/interactive.ts
index 5cc8f7c0dd68..f13eea41af65 100644
--- a/projects/demo/src/modules/components/abstract/interactive.ts
+++ b/projects/demo/src/modules/components/abstract/interactive.ts
@@ -3,7 +3,7 @@ export abstract class AbstractExampleTuiInteractive {
 
     public readonly textAlignVariants: readonly string[] = ['left', 'right'];
 
-    public textAlign = this.textAlignVariants[0];
+    public textAlign = this.textAlignVariants[0]!;
 
     public focusable = true;
 
diff --git a/projects/demo/src/modules/components/accordion/index.ts b/projects/demo/src/modules/components/accordion/index.ts
index 701cfabd5369..89021937c527 100644
--- a/projects/demo/src/modules/components/accordion/index.ts
+++ b/projects/demo/src/modules/components/accordion/index.ts
@@ -81,7 +81,7 @@ export default class Page {
 
     protected readonly sizeVariants: readonly TuiSizeS[] = ['s', 'm'];
 
-    protected size: TuiSizeS = this.sizeVariants[1];
+    protected size: TuiSizeS = this.sizeVariants[1]!;
 
     protected onOpenChange(open: boolean): void {
         this.open = open;
diff --git a/projects/demo/src/modules/components/alert/index.ts b/projects/demo/src/modules/components/alert/index.ts
index 1a569d744578..1988636522df 100644
--- a/projects/demo/src/modules/components/alert/index.ts
+++ b/projects/demo/src/modules/components/alert/index.ts
@@ -56,19 +56,19 @@ export default class Page {
 
     protected readonly appearanceVariants = ['info', 'success', 'error', 'warning'];
 
-    protected appearance = this.appearanceVariants[0];
+    protected appearance = this.appearanceVariants[0]!;
 
     protected readonly iconVariants = ['Default', '@tui.heart'];
 
-    protected icon = this.iconVariants[0];
+    protected icon = this.iconVariants[0]!;
 
     protected readonly contentVariants = ['String', 'Component'];
 
-    protected content = this.contentVariants[0];
+    protected content = this.contentVariants[0]!;
 
     protected readonly autoCloseVariants = [0, 3000, 5000, 1000, 500];
 
-    protected autoClose = this.autoCloseVariants[1];
+    protected autoClose = this.autoCloseVariants[1]!;
 
     protected closeable = true;
 
diff --git a/projects/demo/src/modules/components/arc-chart/index.ts b/projects/demo/src/modules/components/arc-chart/index.ts
index 107fac6b831f..653eccc49530 100644
--- a/projects/demo/src/modules/components/arc-chart/index.ts
+++ b/projects/demo/src/modules/components/arc-chart/index.ts
@@ -20,15 +20,15 @@ export default class Page {
         [13769, 10172, 3018, 2592],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 
     protected readonly maxVariants = [100, 10000, 50000];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected readonly sizeVariants: readonly TuiSizeXL[] = ['m', 'l', 'xl'];
 
-    protected size = this.sizeVariants[0];
+    protected size = this.sizeVariants[0]!;
 
     protected minLabel = '0%';
 
diff --git a/projects/demo/src/modules/components/avatar/index.ts b/projects/demo/src/modules/components/avatar/index.ts
index 4bf79810a562..79fbe25fe153 100644
--- a/projects/demo/src/modules/components/avatar/index.ts
+++ b/projects/demo/src/modules/components/avatar/index.ts
@@ -34,7 +34,7 @@ export default class Page {
         'xxl',
     ];
 
-    protected size = this.sizes[3];
+    protected size = this.sizes[3]!;
 
     protected readonly srcVariants: ReadonlyArray<SafeResourceUrl | string> = [
         'MW',
@@ -46,7 +46,7 @@ export default class Page {
         ),
     ];
 
-    protected src = this.srcVariants[0];
+    protected src = this.srcVariants[0]!;
 
     protected round = true;
 }
diff --git a/projects/demo/src/modules/components/axes/examples/2/index.html b/projects/demo/src/modules/components/axes/examples/2/index.html
index d1444a7b1298..0098bef4288e 100644
--- a/projects/demo/src/modules/components/axes/examples/2/index.html
+++ b/projects/demo/src/modules/components/axes/examples/2/index.html
@@ -29,6 +29,6 @@
             [style.background]="'var(--tui-chart-categorical-0' + index + ')'"
         ></span>
         <span class="name">{{ getSetName(index) }}</span>
-        <span>{{ item[setIndex] * 1000 | tuiAmount: 'RUB' | async }}</span>
+        <span>{{ (item[setIndex] || 0) * 1000 | tuiAmount: 'RUB' | async }}</span>
     </p>
 </ng-template>
diff --git a/projects/demo/src/modules/components/axes/examples/2/index.ts b/projects/demo/src/modules/components/axes/examples/2/index.ts
index d936cb20ba3f..63bc864db2f9 100644
--- a/projects/demo/src/modules/components/axes/examples/2/index.ts
+++ b/projects/demo/src/modules/components/axes/examples/2/index.ts
@@ -51,7 +51,7 @@ export default class Example {
     }
 
     protected getSetName(index: number): string {
-        return this.setNames[index];
+        return this.setNames[index] ?? '';
     }
 
     @tuiPure
diff --git a/projects/demo/src/modules/components/axes/index.ts b/projects/demo/src/modules/components/axes/index.ts
index 07f5d49e60f4..b212f20d1378 100644
--- a/projects/demo/src/modules/components/axes/index.ts
+++ b/projects/demo/src/modules/components/axes/index.ts
@@ -41,29 +41,29 @@ export default class Page {
         (index) => (index % 2 ? 'dashed' : 'solid'),
     ];
 
-    protected axisX = this.lineVariants[0];
+    protected axisX = this.lineVariants[0]!;
 
-    protected axisXLabels = this.labelsXVariants[0];
+    protected axisXLabels = this.labelsXVariants[0]!;
 
-    protected axisY = this.lineVariants[0];
+    protected axisY = this.lineVariants[0]!;
 
     protected axisYInset = false;
 
-    protected axisYLabels = this.labelsYVariants[0];
+    protected axisYLabels = this.labelsYVariants[0]!;
 
     protected axisYName = '';
 
     protected axisYSecondaryInset = false;
 
-    protected axisYSecondaryLabels = this.labelsYVariants[0];
+    protected axisYSecondaryLabels = this.labelsYVariants[0]!;
 
     protected axisYSecondaryName = '';
 
     protected horizontalLines = 0;
 
-    protected horizontalLinesHandler = this.handlerVariants[0];
+    protected horizontalLinesHandler = this.handlerVariants[0]!;
 
     protected verticalLines = 0;
 
-    protected verticalLinesHandler = this.handlerVariants[1];
+    protected verticalLinesHandler = this.handlerVariants[1]!;
 }
diff --git a/projects/demo/src/modules/components/badge-notification/index.ts b/projects/demo/src/modules/components/badge-notification/index.ts
index cba850a325fc..b24415da910b 100644
--- a/projects/demo/src/modules/components/badge-notification/index.ts
+++ b/projects/demo/src/modules/components/badge-notification/index.ts
@@ -19,5 +19,5 @@ export default class Example {
         'xs',
     ];
 
-    protected size: TuiSizeL | TuiSizeXS = this.sizeVariants[0];
+    protected size: TuiSizeL | TuiSizeXS = this.sizeVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/badge/index.ts b/projects/demo/src/modules/components/badge/index.ts
index f8828387ea6b..43349dc3a15e 100644
--- a/projects/demo/src/modules/components/badge/index.ts
+++ b/projects/demo/src/modules/components/badge/index.ts
@@ -52,7 +52,7 @@ export default class Page {
         'neutral',
     ];
 
-    protected appearance = this.appearanceVariants[0];
+    protected appearance = this.appearanceVariants[0]!;
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeS | TuiSizeXL> = [
         's',
@@ -61,8 +61,8 @@ export default class Page {
         'xl',
     ];
 
-    protected size: TuiSizeS | TuiSizeXL = this.sizeVariants[1];
+    protected size: TuiSizeS | TuiSizeXL = this.sizeVariants[1]!;
 
     protected contentTypeVariants = ['text', 'with icon', 'image'];
-    protected contentType = this.contentTypeVariants[0];
+    protected contentType = this.contentTypeVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/badged-content/index.ts b/projects/demo/src/modules/components/badged-content/index.ts
index 34fb6e35a41a..8755afc1607b 100644
--- a/projects/demo/src/modules/components/badged-content/index.ts
+++ b/projects/demo/src/modules/components/badged-content/index.ts
@@ -20,7 +20,7 @@ import {TuiAvatar, TuiBadgedContent, TuiBadgeNotification} from '@taiga-ui/kit';
 })
 export default class Example {
     protected radiusVariants = ['0.75rem', '50%'];
-    protected radius = this.radiusVariants[0];
+    protected radius = this.radiusVariants[0]!;
 
     protected readonly examples = [
         'Basic',
diff --git a/projects/demo/src/modules/components/bar-chart/examples/2/index.ts b/projects/demo/src/modules/components/bar-chart/examples/2/index.ts
index bfd1e935057b..c41c3ab39cfe 100644
--- a/projects/demo/src/modules/components/bar-chart/examples/2/index.ts
+++ b/projects/demo/src/modules/components/bar-chart/examples/2/index.ts
@@ -34,10 +34,13 @@ export default class Example {
     protected readonly labelsY = ['0', '10 000'];
     protected readonly appearances = ['dark', 'error'];
 
-    protected appearance = this.appearances[0];
+    protected appearance = this.appearances[0]!;
 
     protected readonly hint = ({$implicit}: TuiContext<number>): string =>
         this.value
-            .reduce((result, set) => `${result}$${tuiFormatNumber(set[$implicit])}\n`, '')
+            .reduce(
+                (result, set) => `${result}$${tuiFormatNumber(set[$implicit] ?? 0)}\n`,
+                '',
+            )
             .trim();
 }
diff --git a/projects/demo/src/modules/components/bar-chart/index.ts b/projects/demo/src/modules/components/bar-chart/index.ts
index 3d0571fdddc4..7d513774fe81 100644
--- a/projects/demo/src/modules/components/bar-chart/index.ts
+++ b/projects/demo/src/modules/components/bar-chart/index.ts
@@ -33,6 +33,6 @@ export default class Page {
         ],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
     protected readonly routes = DemoRoute;
 }
diff --git a/projects/demo/src/modules/components/bar-set/index.ts b/projects/demo/src/modules/components/bar-set/index.ts
index 6513a66d9230..fa95b8034723 100644
--- a/projects/demo/src/modules/components/bar-set/index.ts
+++ b/projects/demo/src/modules/components/bar-set/index.ts
@@ -31,5 +31,5 @@ export default class Page {
         [237, -50, 10, 5, 1],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/bar/index.ts b/projects/demo/src/modules/components/bar/index.ts
index 1d425494441a..c796ace06c53 100644
--- a/projects/demo/src/modules/components/bar/index.ts
+++ b/projects/demo/src/modules/components/bar/index.ts
@@ -16,12 +16,12 @@ export default class Page {
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
 
-    protected size = this.sizeVariants[1];
+    protected size = this.sizeVariants[1]!;
 
     protected readonly valueVariants = [
         [30, 20, 10],
         [237, 50, 10, 5, 1],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/breadcrumbs/examples/2/index.html b/projects/demo/src/modules/components/breadcrumbs/examples/2/index.html
index 3b8b057d1fd9..c34a3deb1ddb 100644
--- a/projects/demo/src/modules/components/breadcrumbs/examples/2/index.html
+++ b/projects/demo/src/modules/components/breadcrumbs/examples/2/index.html
@@ -15,9 +15,9 @@
             <a
                 *tuiRepeatTimes="let index of items.length - max"
                 tuiOption
-                [href]="items[index].link"
+                [href]="items[index]?.link"
             >
-                {{ items[index].caption }}
+                {{ items[index]?.caption }}
             </a>
         </tui-data-list>
     </ng-template>
@@ -26,9 +26,9 @@
             *tuiItem
             appearance="link"
             tuiLink
-            [href]="items[index + items.length - max].link"
+            [href]="items[index + items.length - max]?.link"
         >
-            {{ items[index + items.length - max].caption }}
+            {{ items[index + items.length - max]?.caption }}
         </a>
     </ng-container>
 </tui-breadcrumbs>
diff --git a/projects/demo/src/modules/components/breadcrumbs/index.ts b/projects/demo/src/modules/components/breadcrumbs/index.ts
index 99dc8146c51f..0ffe1625c54b 100644
--- a/projects/demo/src/modules/components/breadcrumbs/index.ts
+++ b/projects/demo/src/modules/components/breadcrumbs/index.ts
@@ -34,11 +34,11 @@ export default class Example {
         ],
     ];
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     protected readonly sizeVariants: readonly TuiSizeL[] = ['m', 'l'];
 
-    protected size: TuiSizeL = this.sizeVariants[0];
+    protected size: TuiSizeL = this.sizeVariants[0]!;
 
     protected readonly examples = [
         {name: 'Basic'},
diff --git a/projects/demo/src/modules/components/button/index.ts b/projects/demo/src/modules/components/button/index.ts
index 501b528accc9..ed6ac8f0e480 100644
--- a/projects/demo/src/modules/components/button/index.ts
+++ b/projects/demo/src/modules/components/button/index.ts
@@ -23,7 +23,7 @@ export default class Page {
 
     protected readonly sizes: ReadonlyArray<TuiSizeL | TuiSizeXS> = ['xs', 's', 'm', 'l'];
 
-    protected size = this.sizes[3];
+    protected size = this.sizes[3]!;
 
     protected readonly appearances = [
         'primary',
@@ -37,12 +37,12 @@ export default class Page {
         'floating',
     ];
 
-    protected appearance = this.appearances[0];
+    protected appearance = this.appearances[0]!;
 
     protected readonly icons = ['', '@tui.search', '@tui.chevron-down'];
 
-    protected iconStart = this.icons[0];
-    protected iconEnd = this.icons[0];
+    protected iconStart = this.icons[0]!;
+    protected iconEnd = this.icons[0]!;
 
     protected loading = false;
 }
diff --git a/projects/demo/src/modules/components/calendar-month/index.ts b/projects/demo/src/modules/components/calendar-month/index.ts
index 51a58e3063b4..5db7c64495d2 100644
--- a/projects/demo/src/modules/components/calendar-month/index.ts
+++ b/projects/demo/src/modules/components/calendar-month/index.ts
@@ -39,8 +39,8 @@ export default class Example {
         new TuiMonth(2019, 4),
     ];
 
-    protected min = this.minVariants[0];
-    protected max = this.maxVariants[0];
+    protected min = this.minVariants[0]!;
+    protected max = this.maxVariants[0]!;
     protected maxLength = 0;
     protected minLength = 0;
 
@@ -48,7 +48,7 @@ export default class Example {
         TuiBooleanHandler<TuiMonth>
     > = [TUI_FALSE_HANDLER, ({month}) => month % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly valueVariants: ReadonlyArray<TuiMonth | TuiMonthRange> = [
         TuiDay.currentLocal(),
@@ -66,6 +66,6 @@ export default class Example {
         new TuiYear(2007),
     ];
 
-    protected year = this.yearVariants[0];
+    protected year = this.yearVariants[0]!;
     protected readonly routes = DemoRoute;
 }
diff --git a/projects/demo/src/modules/components/calendar-range/examples/5/index.ts b/projects/demo/src/modules/components/calendar-range/examples/5/index.ts
index 3be44d21ca46..09d5e1435645 100644
--- a/projects/demo/src/modules/components/calendar-range/examples/5/index.ts
+++ b/projects/demo/src/modules/components/calendar-range/examples/5/index.ts
@@ -33,7 +33,7 @@ export default class Example {
     protected value: TuiDayRange | null = this.default.range;
 
     public get default(): TuiDayRangePeriod {
-        return this.items[0];
+        return this.items[0]!;
     }
 
     public get isDefault(): boolean {
@@ -57,9 +57,9 @@ export default class Example {
             case this.default:
                 return null;
             case this.items[1]:
-                return this.items[2];
+                return this.items[2]!;
             case this.items[2]:
-                return this.items[3];
+                return this.items[3]!;
             case this.items[3]:
                 return null;
             default:
diff --git a/projects/demo/src/modules/components/calendar-range/index.ts b/projects/demo/src/modules/components/calendar-range/index.ts
index b423518b46df..f28d1035a935 100644
--- a/projects/demo/src/modules/components/calendar-range/index.ts
+++ b/projects/demo/src/modules/components/calendar-range/index.ts
@@ -77,12 +77,12 @@ export default class Example {
     ];
 
     protected markerHandler: TuiMarkerHandler | null = null;
-    protected min: TuiDay = this.minVariants[0];
-    protected max: TuiDay = this.maxVariants[0];
+    protected min: TuiDay = this.minVariants[0]!;
+    protected max: TuiDay = this.maxVariants[0]!;
     protected cleaner = false;
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
-    protected items = this.itemsVariants[0];
-    protected defaultViewedMonth = this.defaultViewedMonthVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
+    protected items = this.itemsVariants[0]!;
+    protected defaultViewedMonth = this.defaultViewedMonthVariants[0]!;
     protected minLength: TuiDayLike | null = null;
     protected maxLength: TuiDayLike | null = null;
     protected readonly routes = DemoRoute;
diff --git a/projects/demo/src/modules/components/calendar/index.ts b/projects/demo/src/modules/components/calendar/index.ts
index 38fc20423c2b..6518f082064c 100644
--- a/projects/demo/src/modules/components/calendar/index.ts
+++ b/projects/demo/src/modules/components/calendar/index.ts
@@ -46,7 +46,7 @@ export default class Example {
         new TuiDay(1900, 0, 1),
     ];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected readonly maxVariants = [
         TUI_LAST_DAY,
@@ -54,7 +54,7 @@ export default class Example {
         new TuiDay(2300, 0, 1),
     ];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected readonly minViewedMonthVariants = [
         new TuiMonth(0, 0),
@@ -62,7 +62,7 @@ export default class Example {
         new TuiMonth(1900, 0),
     ];
 
-    protected minViewedMonth = this.minViewedMonthVariants[0];
+    protected minViewedMonth = this.minViewedMonthVariants[0]!;
 
     protected readonly maxViewedMonthVariants = [
         TUI_LAST_DAY,
@@ -70,13 +70,13 @@ export default class Example {
         new TuiMonth(2300, 0),
     ];
 
-    protected maxViewedMonth = this.maxViewedMonthVariants[0];
+    protected maxViewedMonth = this.maxViewedMonthVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly markerHandlerVariants: readonly TuiMarkerHandler[] = [
         (day: TuiDay) => (day.day % 2 === 0 ? TWO_DOTS : ONE_DOT),
diff --git a/projects/demo/src/modules/components/carousel/index.ts b/projects/demo/src/modules/components/carousel/index.ts
index 5a024b315c0c..32298a86950c 100644
--- a/projects/demo/src/modules/components/carousel/index.ts
+++ b/projects/demo/src/modules/components/carousel/index.ts
@@ -24,8 +24,8 @@ export default class Example {
     protected readonly durationVariants = [0, 3000, 10000];
     protected readonly itemPaddingVariants = [null, '0 10px', '0'];
     protected draggable = false;
-    protected duration = this.durationVariants[0];
-    protected itemPadding: string | null = this.itemPaddingVariants[0];
+    protected duration = this.durationVariants[0]!;
+    protected itemPadding: string | null = this.itemPaddingVariants[0]!;
     protected index = 0;
     protected itemsCount = 1;
 }
diff --git a/projects/demo/src/modules/components/cell/examples/7/index.ts b/projects/demo/src/modules/components/cell/examples/7/index.ts
index 1db266e41412..1ef8e5dc0879 100644
--- a/projects/demo/src/modules/components/cell/examples/7/index.ts
+++ b/projects/demo/src/modules/components/cell/examples/7/index.ts
@@ -47,5 +47,5 @@ export default class Example {
         },
     ];
 
-    protected value = this.items[0];
+    protected value = this.items[0]!;
 }
diff --git a/projects/demo/src/modules/components/cell/examples/8/index.ts b/projects/demo/src/modules/components/cell/examples/8/index.ts
index 5770f333044a..45351a28ccfa 100644
--- a/projects/demo/src/modules/components/cell/examples/8/index.ts
+++ b/projects/demo/src/modules/components/cell/examples/8/index.ts
@@ -59,7 +59,7 @@ export default class Example {
         },
     ];
 
-    protected value = this.items[0];
+    protected value = this.items[0]!;
 
     protected incoming = false;
     protected outgoing = true;
diff --git a/projects/demo/src/modules/components/combo-box/index.ts b/projects/demo/src/modules/components/combo-box/index.ts
index 23d126bc9d21..7c7756d0ac1c 100644
--- a/projects/demo/src/modules/components/combo-box/index.ts
+++ b/projects/demo/src/modules/components/combo-box/index.ts
@@ -99,7 +99,7 @@ export default class Example extends AbstractExampleTuiControl {
         (item) => String(String(item).match(/\d+/)),
     ];
 
-    protected stringify = this.stringifyVariants[0];
+    protected stringify = this.stringifyVariants[0]!;
 
     protected readonly strictMatcherVariants: ReadonlyArray<TuiStringMatcher<Account>> = [
         TUI_STRICT_MATCHER as TuiStringMatcher<Account>,
@@ -108,7 +108,7 @@ export default class Example extends AbstractExampleTuiControl {
             Number.parseInt(search, 10),
     ];
 
-    protected strictMatcher = this.strictMatcherVariants[0];
+    protected strictMatcher = this.strictMatcherVariants[0]!;
 
     protected readonly identityMatcherVariants: ReadonlyArray<
         TuiIdentityMatcher<Account>
@@ -117,13 +117,13 @@ export default class Example extends AbstractExampleTuiControl {
         (item1, item2) => item1.balance === item2.balance,
     ];
 
-    protected identityMatcher = this.identityMatcherVariants[0];
+    protected identityMatcher = this.identityMatcherVariants[0]!;
 
     public readonly control = new FormControl<Account | null>(null, Validators.required);
 
     public readonly iconVariants = ['', '@tui.pie-chart', '@tui.credit-card'];
 
-    public override iconStart = this.iconVariants[0];
+    public override iconStart = this.iconVariants[0]!;
 
     protected get valueContent(): PolymorpheusContent<TuiValueContentContext<Account>> {
         return this.valueTemplateRef && this.selectedValueTemplate
diff --git a/projects/demo/src/modules/components/compass/index.ts b/projects/demo/src/modules/components/compass/index.ts
index 104df7ee9436..7118a896ec84 100644
--- a/projects/demo/src/modules/components/compass/index.ts
+++ b/projects/demo/src/modules/components/compass/index.ts
@@ -17,7 +17,7 @@ export default class Page {
         '',
     ];
 
-    protected color = this.colorVariants[0];
+    protected color = this.colorVariants[0]!;
 
     protected degrees = 90;
 }
diff --git a/projects/demo/src/modules/components/confirm/index.ts b/projects/demo/src/modules/components/confirm/index.ts
index 04eb2b48123d..638ebe74d9ed 100644
--- a/projects/demo/src/modules/components/confirm/index.ts
+++ b/projects/demo/src/modules/components/confirm/index.ts
@@ -22,7 +22,7 @@ export default class Example implements TuiConfirmData {
     protected readonly exampleService = import('./examples/import/service.md?raw');
 
     public readonly appearances = ['primary', 'accent', 'secondary'];
-    public appearance = this.appearances[0];
+    public appearance = this.appearances[0]!;
     public no = 'No';
     public yes = 'Yes';
 
diff --git a/projects/demo/src/modules/components/dialog/examples/9/helpers/pay.service.ts b/projects/demo/src/modules/components/dialog/examples/9/helpers/pay.service.ts
index f2126b1f62fd..91de4ad18e79 100644
--- a/projects/demo/src/modules/components/dialog/examples/9/helpers/pay.service.ts
+++ b/projects/demo/src/modules/components/dialog/examples/9/helpers/pay.service.ts
@@ -19,7 +19,7 @@ export class PayService {
     public getPrimaryCard(): Observable<FetchedCards> {
         return timer(this.getRandomDelay()).pipe(
             map(() => MOCK_CARDS),
-            map((cards: AccountCard[]) => ({primary: cards[0], cards})),
+            map((cards: AccountCard[]) => ({primary: cards[0]!, cards})),
         );
     }
 
diff --git a/projects/demo/src/modules/components/dialog/index.ts b/projects/demo/src/modules/components/dialog/index.ts
index 729c60720d2a..87e979f2a74a 100644
--- a/projects/demo/src/modules/components/dialog/index.ts
+++ b/projects/demo/src/modules/components/dialog/index.ts
@@ -100,7 +100,7 @@ export default class Page {
         'auto',
     ];
 
-    protected size: TuiDialogSize = this.sizeVariants[1];
+    protected size: TuiDialogSize = this.sizeVariants[1]!;
 
     protected label = '';
 
diff --git a/projects/demo/src/modules/components/error/index.ts b/projects/demo/src/modules/components/error/index.ts
index aadc0c565e29..a9e9357772a4 100644
--- a/projects/demo/src/modules/components/error/index.ts
+++ b/projects/demo/src/modules/components/error/index.ts
@@ -20,7 +20,7 @@ export default class Page {
         'Error as HTML content',
     ];
 
-    protected selectedError = this.errorVariants[0];
+    protected selectedError = this.errorVariants[0]!;
 
     protected get error(): TuiValidationError | string | null {
         if (this.selectedError === null) {
diff --git a/projects/demo/src/modules/components/filter/examples/3/index.ts b/projects/demo/src/modules/components/filter/examples/3/index.ts
index 29917d20931f..18d67e62a150 100644
--- a/projects/demo/src/modules/components/filter/examples/3/index.ts
+++ b/projects/demo/src/modules/components/filter/examples/3/index.ts
@@ -30,6 +30,6 @@ export default class Example {
     });
 
     protected getItemIcon(title: string): string {
-        return getIcon[title];
+        return getIcon[title] ?? '';
     }
 }
diff --git a/projects/demo/src/modules/components/filter/index.ts b/projects/demo/src/modules/components/filter/index.ts
index efc2aec2ff38..e30a513d758d 100644
--- a/projects/demo/src/modules/components/filter/index.ts
+++ b/projects/demo/src/modules/components/filter/index.ts
@@ -46,7 +46,7 @@ export default class Page {
         (item) => String(item).length,
     ];
 
-    protected badgeHandler = this.badgeHandlerVariants[0];
+    protected badgeHandler = this.badgeHandlerVariants[0]!;
 
     protected disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<ItemWithBadge | string>
@@ -56,13 +56,13 @@ export default class Page {
         (item) => (Number(item.valueOf()) || 0) >= 30,
     ];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     protected control = new FormControl(this.initialItems);
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
 
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
 }
diff --git a/projects/demo/src/modules/components/group/index.ts b/projects/demo/src/modules/components/group/index.ts
index 55547eae4013..e3878fca1b27 100644
--- a/projects/demo/src/modules/components/group/index.ts
+++ b/projects/demo/src/modules/components/group/index.ts
@@ -21,10 +21,10 @@ export default class Page {
         'vertical',
     ];
 
-    protected orientation: TuiOrientation = this.orientationVariants[0];
+    protected orientation: TuiOrientation = this.orientationVariants[0]!;
 
     protected readonly sizeVariants: readonly TuiSizeL[] = ['m', 'l'];
 
-    protected size: TuiSizeL = this.sizeVariants[1];
+    protected size: TuiSizeL = this.sizeVariants[1]!;
     protected readonly routes = DemoRoute;
 }
diff --git a/projects/demo/src/modules/components/icon/index.ts b/projects/demo/src/modules/components/icon/index.ts
index 483566588323..e3d72aac71c0 100644
--- a/projects/demo/src/modules/components/icon/index.ts
+++ b/projects/demo/src/modules/components/icon/index.ts
@@ -34,7 +34,7 @@ export default class Page {
 
     protected icon = '@tui.heart';
     protected backgroundIcon = '';
-    protected color = this.colorVariants[1];
+    protected color = this.colorVariants[1]!;
     protected backgroundColor = '';
     protected size = 24;
 }
diff --git a/projects/demo/src/modules/components/input-copy/index.ts b/projects/demo/src/modules/components/input-copy/index.ts
index ae7b87449600..00f430fc24bb 100644
--- a/projects/demo/src/modules/components/input-copy/index.ts
+++ b/projects/demo/src/modules/components/input-copy/index.ts
@@ -33,10 +33,10 @@ export default class PageComponent extends AbstractExampleTuiControl {
 
     protected readonly successMessageVariants = ['Copied', 'Template'];
 
-    protected successMessage = this.successMessageVariants[0];
+    protected successMessage = this.successMessageVariants[0]!;
 
-    protected messageDirection = this.hintDirectionVariants[0];
-    protected messageMode = this.hintAppearanceVariants[0];
+    protected messageDirection = this.hintDirectionVariants[0]!;
+    protected messageMode = this.hintAppearanceVariants[0]!;
 
     public readonly control = new FormControl('', Validators.required);
 
diff --git a/projects/demo/src/modules/components/input-date-multi/index.ts b/projects/demo/src/modules/components/input-date-multi/index.ts
index 8d913a75e6f7..049919c47498 100644
--- a/projects/demo/src/modules/components/input-date-multi/index.ts
+++ b/projects/demo/src/modules/components/input-date-multi/index.ts
@@ -47,7 +47,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiDay(new Date().getFullYear() + 3, 1, 1),
     ];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected maxVariants = [
         TUI_LAST_DAY,
@@ -56,17 +56,17 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiDay(2300, 0, 1),
     ];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected rowsVariants = [Infinity, 10, 3, 2];
 
-    protected rows = this.rowsVariants[0];
+    protected rows = this.rowsVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly markerHandlerVariants: readonly TuiMarkerHandler[] = [
         (day: TuiDay) =>
diff --git a/projects/demo/src/modules/components/input-date-range/index.ts b/projects/demo/src/modules/components/input-date-range/index.ts
index fd51df503dfc..ed2925f706ad 100644
--- a/projects/demo/src/modules/components/input-date-range/index.ts
+++ b/projects/demo/src/modules/components/input-date-range/index.ts
@@ -59,13 +59,13 @@ export default class PageComponent extends AbstractExampleTuiControl {
         TUI_LAST_DAY,
     ];
 
-    protected min: TuiDay = this.dayVariants[0];
+    protected min: TuiDay = this.dayVariants[0]!;
 
     protected readonly minLengthVariants: readonly TuiDayLike[] = [{day: 3}, {day: 15}];
 
     protected minLength: TuiDayLike | null = null;
 
-    protected max = this.dayVariants[this.dayVariants.length - 1];
+    protected max = this.dayVariants[this.dayVariants.length - 1]!;
 
     protected readonly markerHandlerVariants: readonly TuiMarkerHandler[] = [
         (day: TuiDay) => (day.day % 2 === 0 ? TWO_DOTS : ONE_DOT),
@@ -77,14 +77,14 @@ export default class PageComponent extends AbstractExampleTuiControl {
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly itemsVariants: ReadonlyArray<readonly TuiDayRangePeriod[]> = [
         [],
         tuiCreateDefaultDayRangePeriods(),
     ];
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     protected readonly defaultViewedMonthVariants: readonly TuiMonth[] = [
         TuiMonth.currentLocal(),
@@ -92,7 +92,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiMonth(2007, 5),
     ];
 
-    protected defaultViewedMonth = this.defaultViewedMonthVariants[0];
+    protected defaultViewedMonth = this.defaultViewedMonthVariants[0]!;
 
     public override cleaner = false;
     public control = new FormControl<TuiDayRange | null>(null, Validators.required);
diff --git a/projects/demo/src/modules/components/input-date-time/index.ts b/projects/demo/src/modules/components/input-date-time/index.ts
index c8d48867c87b..2de688b074dd 100644
--- a/projects/demo/src/modules/components/input-date-time/index.ts
+++ b/projects/demo/src/modules/components/input-date-time/index.ts
@@ -51,7 +51,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         [this.today.append({day: -1}), new TuiTime(12, 20)],
     ];
 
-    protected min: TuiDay | [TuiDay, TuiTime] = this.minVariants[0];
+    protected min: TuiDay | [TuiDay, TuiTime] = this.minVariants[0]!;
 
     protected readonly maxVariants: ReadonlyArray<TuiDay | [TuiDay, TuiTime]> = [
         TUI_LAST_DAY,
@@ -61,7 +61,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         [this.today.append({day: +1}), new TuiTime(16, 20)],
     ];
 
-    protected max: TuiDay | [TuiDay, TuiTime] = this.maxVariants[0];
+    protected max: TuiDay | [TuiDay, TuiTime] = this.maxVariants[0]!;
 
     protected defaultActiveYearMonthVariants = [
         TuiMonth.currentLocal(),
@@ -69,20 +69,20 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiMonth(2017, 2),
     ];
 
-    protected defaultActiveYearMonth = this.defaultActiveYearMonthVariants[0];
+    protected defaultActiveYearMonth = this.defaultActiveYearMonthVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly itemsVariants = [
         [],
         [new TuiNamedDay(TUI_LAST_DAY.append({year: -1}), 'Until today')],
     ];
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     protected readonly modeVariants: readonly TuiTimeMode[] = [
         'HH:MM',
@@ -90,7 +90,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         'HH:MM:SS.MSS',
     ];
 
-    protected mode = this.modeVariants[0];
+    protected mode = this.modeVariants[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input-date/index.ts b/projects/demo/src/modules/components/input-date/index.ts
index 44e44f8a30f0..49b4e52c41e8 100644
--- a/projects/demo/src/modules/components/input-date/index.ts
+++ b/projects/demo/src/modules/components/input-date/index.ts
@@ -63,7 +63,7 @@ export default class Example extends AbstractExampleTuiControl {
         new TuiDay(new Date().getFullYear() + 3, 1, 1),
     ];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected maxVariants = [
         TUI_LAST_DAY,
@@ -72,13 +72,13 @@ export default class Example extends AbstractExampleTuiControl {
         new TuiDay(2300, 0, 1),
     ];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly itemsVariants = [
         [],
@@ -91,7 +91,7 @@ export default class Example extends AbstractExampleTuiControl {
 
     protected markerHandler: TuiMarkerHandler | null = null;
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input-files/index.ts b/projects/demo/src/modules/components/input-files/index.ts
index ab449ba7b2d8..2c0e8df8fe3d 100644
--- a/projects/demo/src/modules/components/input-files/index.ts
+++ b/projects/demo/src/modules/components/input-files/index.ts
@@ -40,10 +40,10 @@ export default class PageComponent extends AbstractExampleTuiControl {
     ];
 
     protected rejected: readonly File[] = [];
-    protected maxFileSize = this.maxFileSizeVariants[2];
+    protected maxFileSize = this.maxFileSizeVariants[2]!;
 
     public override readonly sizeVariants: readonly TuiSizeL[] = ['m', 'l'];
-    public override size = this.sizeVariants[0];
+    public override size = this.sizeVariants[0]!;
     public readonly control = new FormControl<File[] | null>(null);
     public readonly files$ = this.control.valueChanges.pipe(
         map(() => tuiFilesAccepted(this.control)),
diff --git a/projects/demo/src/modules/components/input-month-range/index.ts b/projects/demo/src/modules/components/input-month-range/index.ts
index a99b3e1f1f2a..5247449b6853 100644
--- a/projects/demo/src/modules/components/input-month-range/index.ts
+++ b/projects/demo/src/modules/components/input-month-range/index.ts
@@ -47,15 +47,15 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiMonth(2023, 0),
     ];
 
-    protected min = this.minVariants[0];
-    protected max = this.maxVariants[0];
+    protected min = this.minVariants[0]!;
+    protected max = this.maxVariants[0]!;
     protected minLength = 0;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiMonth>
     > = [TUI_FALSE_HANDLER, ({month}) => month % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     public override cleaner = false;
     public override maxLength = 0;
diff --git a/projects/demo/src/modules/components/input-month/index.ts b/projects/demo/src/modules/components/input-month/index.ts
index f3f9ac7c9929..fe9e4fb8b995 100644
--- a/projects/demo/src/modules/components/input-month/index.ts
+++ b/projects/demo/src/modules/components/input-month/index.ts
@@ -45,14 +45,14 @@ export default class PageComponent extends AbstractExampleTuiControl {
         new TuiMonth(2023, 0),
     ];
 
-    protected min = this.minVariants[0];
-    protected max = this.maxVariants[0];
+    protected min = this.minVariants[0]!;
+    protected max = this.maxVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiMonth>
     > = [TUI_FALSE_HANDLER, ({month}) => month % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input-number/index.ts b/projects/demo/src/modules/components/input-number/index.ts
index 1b6d63c3d982..5ce6ad3c08f8 100644
--- a/projects/demo/src/modules/components/input-number/index.ts
+++ b/projects/demo/src/modules/components/input-number/index.ts
@@ -32,11 +32,11 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
 
     protected readonly minVariants: readonly number[] = [-Infinity, -500, 5, 25];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected readonly maxVariants: readonly number[] = [Infinity, 10, 500];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected step = 0;
 
diff --git a/projects/demo/src/modules/components/input-phone-international/index.ts b/projects/demo/src/modules/components/input-phone-international/index.ts
index a1ae046b9bbd..16100c310c1c 100644
--- a/projects/demo/src/modules/components/input-phone-international/index.ts
+++ b/projects/demo/src/modules/components/input-phone-international/index.ts
@@ -41,7 +41,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         getCountries(),
     ];
 
-    protected countries = this.countriesVariants[0];
+    protected countries = this.countriesVariants[0]!;
 
     protected readonly countryIsoCodeVariants: readonly TuiCountryIsoCode[] = [
         'RU',
@@ -50,7 +50,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         'BY',
     ];
 
-    protected countryIsoCode = this.countryIsoCodeVariants[0];
+    protected countryIsoCode = this.countryIsoCodeVariants[0]!;
 
     public override cleaner = false;
     public control = new FormControl('', [Validators.required, Validators.minLength(9)]);
diff --git a/projects/demo/src/modules/components/input-phone/examples/3/index.ts b/projects/demo/src/modules/components/input-phone/examples/3/index.ts
index c58a171d839c..1b806b02c7da 100644
--- a/projects/demo/src/modules/components/input-phone/examples/3/index.ts
+++ b/projects/demo/src/modules/components/input-phone/examples/3/index.ts
@@ -138,7 +138,7 @@ export default class Example {
     private isFullMatch(response: readonly User[], value: string): boolean {
         return (
             response.length === 1 &&
-            (String(response[0]) === value || response[0].phone === value)
+            (String(response[0]) === value || response[0]?.phone === value)
         );
     }
 }
diff --git a/projects/demo/src/modules/components/input-phone/index.ts b/projects/demo/src/modules/components/input-phone/index.ts
index 3ffb766d4d8c..bea0750d6ee6 100644
--- a/projects/demo/src/modules/components/input-phone/index.ts
+++ b/projects/demo/src/modules/components/input-phone/index.ts
@@ -29,7 +29,7 @@ import {InheritedDocumentation} from '../abstract/inherited-documentation';
 export default class PageComponent extends AbstractExampleTuiControl {
     protected countryCodes = ['+7', '+850', '+1', '+52'];
 
-    protected countryCode = this.countryCodes[0];
+    protected countryCode = this.countryCodes[0]!;
 
     protected phoneMasksAfterCountryCode = [
         '(###) ###-##-##',
@@ -37,7 +37,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         '### ###-####',
     ];
 
-    protected phoneMaskAfterCountryCode = this.phoneMasksAfterCountryCode[0];
+    protected phoneMaskAfterCountryCode = this.phoneMasksAfterCountryCode[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input-range/index.ts b/projects/demo/src/modules/components/input-range/index.ts
index 38c12ffbf524..c0e243d4e641 100644
--- a/projects/demo/src/modules/components/input-range/index.ts
+++ b/projects/demo/src/modules/components/input-range/index.ts
@@ -36,11 +36,11 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
     protected readonly routes = DemoRoute;
     protected minVariants: readonly number[] = [0, 5, 7.77, -10];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected maxVariants: readonly number[] = [10, 100, 10000];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected segments = 1;
 
@@ -48,7 +48,7 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
 
     protected quantumVariants: readonly number[] = [1, 0.001, 10, 100];
 
-    protected quantum = this.quantumVariants[0];
+    protected quantum = this.quantumVariants[0]!;
 
     protected readonly pluralizeVariants: ReadonlyArray<Record<string, string>> = [
         {one: 'thing', few: 'things', many: 'things', other: 'things'},
@@ -78,12 +78,12 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
         ({$implicit: val}: TuiContext<number>) => (val === 5 ? 'FIVE' : `${val}`),
     ];
 
-    protected leftValueContent = this.valueContentVariants[0];
-    protected rightValueContent = this.valueContentVariants[0];
+    protected leftValueContent = this.valueContentVariants[0]!;
+    protected rightValueContent = this.valueContentVariants[0]!;
 
     public control = new FormControl([0, 10]);
 
     public override sizeVariants: readonly TuiSizeL[] = ['m', 'l'];
 
-    public override size = this.sizeVariants[1];
+    public override size = this.sizeVariants[1]!;
 }
diff --git a/projects/demo/src/modules/components/input-slider/index.ts b/projects/demo/src/modules/components/input-slider/index.ts
index 50d445901117..862115835aa1 100644
--- a/projects/demo/src/modules/components/input-slider/index.ts
+++ b/projects/demo/src/modules/components/input-slider/index.ts
@@ -37,11 +37,11 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
     protected readonly routes = DemoRoute;
     protected readonly minVariants: readonly number[] = [0, 1, 5, 7.77, -10];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected readonly maxVariants: readonly number[] = [10, 100, 10000];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected segments = 1;
 
@@ -51,7 +51,7 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
         1, 0.01, 0.001, 0.0001, 10, 20, 100,
     ];
 
-    protected quantum = this.quantumVariants[0];
+    protected quantum = this.quantumVariants[0]!;
 
     protected readonly valueContentVariants = [
         '',
@@ -61,7 +61,7 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
         ({$implicit: val}: TuiContext<number>) => (val === 5 ? 'FIVE' : val),
     ];
 
-    protected valueContent = this.valueContentVariants[0];
+    protected valueContent = this.valueContentVariants[0]!;
 
     protected readonly keyStepsVariants: readonly TuiKeySteps[] = [
         [
@@ -74,7 +74,7 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
     protected keySteps: TuiKeySteps | null = null;
 
     public override readonly sizeVariants: readonly TuiSizeL[] = ['m', 'l'];
-    public override size = this.sizeVariants[1];
+    public override size = this.sizeVariants[1]!;
     public readonly control = new FormControl(0);
 
     public override readonly customContentVariants: string[] = [
@@ -83,5 +83,5 @@ export default class PageComponent extends AbstractExampleTuiNumberFormat {
         '@tui.mastercard-mono',
     ];
 
-    public override customContentSelected = this.customContentVariants[0];
+    public override customContentSelected = this.customContentVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/input-tag/index.ts b/projects/demo/src/modules/components/input-tag/index.ts
index 995801776b1d..1d8b9885b502 100644
--- a/projects/demo/src/modules/components/input-tag/index.ts
+++ b/projects/demo/src/modules/components/input-tag/index.ts
@@ -46,7 +46,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
 
     protected readonly separatorVariants = [',', ';', /[\d]/, /[\s,]/];
 
-    protected separator = this.separatorVariants[0];
+    protected separator = this.separatorVariants[0]!;
 
     protected readonly iconVariants: readonly string[] = ['@tui.search'];
 
@@ -62,7 +62,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         (item) => item !== 'mail',
     ];
 
-    protected tagValidator = this.tagValidatorVariants[0];
+    protected tagValidator = this.tagValidatorVariants[0]!;
 
     protected inputHidden = false;
 
@@ -70,7 +70,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         TuiBooleanHandler<TuiStringifiableItem<string> | string>
     > = [TUI_FALSE_HANDLER, (item) => String(item).startsWith('T')];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     public override readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = [
         's',
@@ -79,7 +79,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
     ];
 
     public override size: TuiSizeL | TuiSizeS =
-        this.sizeVariants[this.sizeVariants.length - 1];
+        this.sizeVariants[this.sizeVariants.length - 1]!;
 
     public readonly control = new FormControl(
         ['John Cleese', 'Eric Idle', 'Michael Palin'],
diff --git a/projects/demo/src/modules/components/input-time/index.ts b/projects/demo/src/modules/components/input-time/index.ts
index 4b78e45e9dde..589ae6e62148 100644
--- a/projects/demo/src/modules/components/input-time/index.ts
+++ b/projects/demo/src/modules/components/input-time/index.ts
@@ -40,7 +40,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         (item: TuiTime) => String(item) === '06:00' || item > TuiTime.currentLocal(),
     ];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected readonly itemSizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = [
         's',
@@ -48,14 +48,14 @@ export default class PageComponent extends AbstractExampleTuiControl {
         'l',
     ];
 
-    protected itemSize: TuiSizeL | TuiSizeS = this.itemSizeVariants[1];
+    protected itemSize: TuiSizeL | TuiSizeS = this.itemSizeVariants[1]!;
 
     protected readonly itemsVariants: ReadonlyArray<readonly TuiTime[]> = [
         [],
         tuiCreateTimePeriods(),
     ];
 
-    protected items = this.itemsVariants[0];
+    protected items = this.itemsVariants[0]!;
 
     protected strict = false;
 
@@ -65,7 +65,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         'HH:MM:SS.MSS',
     ];
 
-    protected mode = this.modeVariants[0];
+    protected mode = this.modeVariants[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input-year/index.ts b/projects/demo/src/modules/components/input-year/index.ts
index 7185845bf2a0..093b82da21b7 100644
--- a/projects/demo/src/modules/components/input-year/index.ts
+++ b/projects/demo/src/modules/components/input-year/index.ts
@@ -27,14 +27,14 @@ export default class PageComponent extends AbstractExampleTuiControl {
     protected readonly minVariants = [TUI_FIRST_DAY.year, 2019, 2007];
     protected readonly maxVariants = [TUI_LAST_DAY.year, 2020, 2023];
 
-    protected min = this.minVariants[0];
-    protected max = this.maxVariants[0];
+    protected min = this.minVariants[0]!;
+    protected max = this.maxVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<number>
     > = [TUI_FALSE_HANDLER, (year) => year % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     public override cleaner = false;
 
diff --git a/projects/demo/src/modules/components/input/examples/4/index.ts b/projects/demo/src/modules/components/input/examples/4/index.ts
index 52cd20248159..d3a9790b58b1 100644
--- a/projects/demo/src/modules/components/input/examples/4/index.ts
+++ b/projects/demo/src/modules/components/input/examples/4/index.ts
@@ -141,7 +141,9 @@ export default class Example {
                 return filtered;
             }
 
-            this.onSelected(filtered[0]);
+            if (filtered[0]) {
+                this.onSelected(filtered[0]);
+            }
 
             return [];
         }),
diff --git a/projects/demo/src/modules/components/input/examples/8/index.ts b/projects/demo/src/modules/components/input/examples/8/index.ts
index c6f39d167213..b8de13618ffe 100644
--- a/projects/demo/src/modules/components/input/examples/8/index.ts
+++ b/projects/demo/src/modules/components/input/examples/8/index.ts
@@ -59,7 +59,11 @@ export default class Example {
         switchMap((value) =>
             this.request(value ?? '').pipe(
                 map((response) => {
-                    if (response.length === 1 && String(response[0]) === value) {
+                    if (
+                        response.length === 1 &&
+                        response[0] &&
+                        String(response[0]) === value
+                    ) {
                         this.onClick(response[0]);
 
                         return [];
diff --git a/projects/demo/src/modules/components/input/index.ts b/projects/demo/src/modules/components/input/index.ts
index 330478523c05..e3205c743f78 100644
--- a/projects/demo/src/modules/components/input/index.ts
+++ b/projects/demo/src/modules/components/input/index.ts
@@ -43,9 +43,9 @@ export default class PageComponent extends AbstractExampleTuiControl {
 
     public readonly iconVariants = ['', '@tui.search', '@tui.calendar'];
 
-    public icon = this.iconVariants[0];
+    public icon = this.iconVariants[0]!;
 
-    public override iconStart = this.iconVariants[0];
+    public override iconStart = this.iconVariants[0]!;
 
     public readonly control = new FormControl('111', Validators.required);
 
diff --git a/projects/demo/src/modules/components/island/index.ts b/projects/demo/src/modules/components/island/index.ts
index 5e63c5cd597c..cf29d7b45359 100644
--- a/projects/demo/src/modules/components/island/index.ts
+++ b/projects/demo/src/modules/components/island/index.ts
@@ -24,6 +24,6 @@ export default class Page {
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
 
-    protected size: TuiSizeL | TuiSizeS = this.sizeVariants[0];
+    protected size: TuiSizeL | TuiSizeS = this.sizeVariants[0]!;
     protected readonly routes = DemoRoute;
 }
diff --git a/projects/demo/src/modules/components/items-with-more/index.ts b/projects/demo/src/modules/components/items-with-more/index.ts
index af970a859a9e..e08a39143931 100644
--- a/projects/demo/src/modules/components/items-with-more/index.ts
+++ b/projects/demo/src/modules/components/items-with-more/index.ts
@@ -16,7 +16,7 @@ export default class Page {
 
     protected readonly itemsLimitVariants = [Infinity, 4, 2];
 
-    protected required = this.requiredVariants[0];
+    protected required = this.requiredVariants[0]!;
 
-    protected itemsLimit = this.itemsLimitVariants[0];
+    protected itemsLimit = this.itemsLimitVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/legend-item/examples/1/index.html b/projects/demo/src/modules/components/legend-item/examples/1/index.html
index caed141343d6..93082ea0f2ed 100644
--- a/projects/demo/src/modules/components/legend-item/examples/1/index.html
+++ b/projects/demo/src/modules/components/legend-item/examples/1/index.html
@@ -17,7 +17,7 @@
             [text]="label"
             (tuiHoveredChange)="onHover(index, $event)"
         >
-            <span>{{ value[index] | tuiAmount: 'RUB' | async }}</span>
+            <span>{{ value[index] || 0 | tuiAmount: 'RUB' | async }}</span>
         </tui-legend-item>
     </div>
 </div>
diff --git a/projects/demo/src/modules/components/legend-item/examples/2/index.html b/projects/demo/src/modules/components/legend-item/examples/2/index.html
index a8a49c45492e..ec341fde95da 100644
--- a/projects/demo/src/modules/components/legend-item/examples/2/index.html
+++ b/projects/demo/src/modules/components/legend-item/examples/2/index.html
@@ -27,7 +27,7 @@
                 type="checkbox"
                 [checked]="!item.disabled"
             />
-            <span>{{ data[index] | tuiAmount: 'RUB' | async }}</span>
+            <span>{{ data[index] || 0 | tuiAmount: 'RUB' | async }}</span>
             <tui-icon
                 icon="@tui.x"
                 class="disable"
diff --git a/projects/demo/src/modules/components/legend-item/examples/2/index.ts b/projects/demo/src/modules/components/legend-item/examples/2/index.ts
index c6041fca72a5..3c15eef6f2b1 100644
--- a/projects/demo/src/modules/components/legend-item/examples/2/index.ts
+++ b/projects/demo/src/modules/components/legend-item/examples/2/index.ts
@@ -48,7 +48,7 @@ export default class Example {
     protected onClick(index: number): void {
         if (this.isEnabled(index)) {
             this.alerts
-                .open(`Category spending: ${tuiFormatNumber(this.data[index])} ₽`, {
+                .open(`Category spending: ${tuiFormatNumber(this.data[index] ?? 0)} ₽`, {
                     label: this.labels[index],
                 })
                 .subscribe();
diff --git a/projects/demo/src/modules/components/legend-item/index.ts b/projects/demo/src/modules/components/legend-item/index.ts
index 5205afac76c8..1bc505e8fc7b 100644
--- a/projects/demo/src/modules/components/legend-item/index.ts
+++ b/projects/demo/src/modules/components/legend-item/index.ts
@@ -24,7 +24,7 @@ export default class Page {
         'var(--tui-background-neutral-1)',
     ];
 
-    protected size = this.sizeVariants[0];
+    protected size = this.sizeVariants[0]!;
 
     protected disabled = false;
 
diff --git a/projects/demo/src/modules/components/line-chart/examples/1/index.ts b/projects/demo/src/modules/components/line-chart/examples/1/index.ts
index cd9efebc016f..d39d39f54b39 100644
--- a/projects/demo/src/modules/components/line-chart/examples/1/index.ts
+++ b/projects/demo/src/modules/components/line-chart/examples/1/index.ts
@@ -28,5 +28,5 @@ export default class Example {
 
     protected readonly hintContent = ({
         $implicit,
-    }: TuiContext<readonly TuiPoint[]>): number => $implicit[0][1];
+    }: TuiContext<readonly TuiPoint[]>): number => $implicit[0]?.[1] ?? 0;
 }
diff --git a/projects/demo/src/modules/components/line-chart/examples/5/index.ts b/projects/demo/src/modules/components/line-chart/examples/5/index.ts
index 1f0326d7c3b3..47eef29ad66f 100644
--- a/projects/demo/src/modules/components/line-chart/examples/5/index.ts
+++ b/projects/demo/src/modules/components/line-chart/examples/5/index.ts
@@ -47,5 +47,5 @@ export default class Example {
 
     protected readonly hint: TuiStringHandler<TuiContext<readonly TuiPoint[]>> = ({
         $implicit,
-    }) => `${$implicit[0][0]} items:\n\n${$implicit.map(([_, y]) => y).join('$\n')}$`;
+    }) => `${$implicit[0]?.[0]} items:\n\n${$implicit.map(([_, y]) => y).join('$\n')}$`;
 }
diff --git a/projects/demo/src/modules/components/line-days-chart/examples/1/index.ts b/projects/demo/src/modules/components/line-days-chart/examples/1/index.ts
index d52e6ab93375..56fa26bf6ff7 100644
--- a/projects/demo/src/modules/components/line-days-chart/examples/1/index.ts
+++ b/projects/demo/src/modules/components/line-days-chart/examples/1/index.ts
@@ -59,7 +59,7 @@ export default class Example {
             map((months) => [
                 ...Array.from(
                     {length: TuiMonth.lengthBetween(from, to) + 1},
-                    (_, i) => months[from.append({month: i}).month],
+                    (_, i) => months[from.append({month: i}).month] ?? '',
                 ),
                 null,
             ]),
@@ -75,6 +75,6 @@ export default class Example {
             .fill(0)
             .reduce<
                 ReadonlyArray<[TuiDay, number]>
-            >((array, _, i) => [...array, [from.append({day: i}), this.isE2E ? 100 : (i ? array[i - 1][1] : 100) + Math.random() * 10 - 5]], []);
+            >((array, _, i) => [...array, [from.append({day: i}), this.isE2E ? 100 : (i ? (array[i - 1]?.[1] ?? 0) : 100) + Math.random() * 10 - 5]], []);
     }
 }
diff --git a/projects/demo/src/modules/components/line-days-chart/examples/2/index.ts b/projects/demo/src/modules/components/line-days-chart/examples/2/index.ts
index 276834357fda..5f1d6f616677 100644
--- a/projects/demo/src/modules/components/line-days-chart/examples/2/index.ts
+++ b/projects/demo/src/modules/components/line-days-chart/examples/2/index.ts
@@ -82,7 +82,7 @@ export default class Example {
                 map((months) => [
                     ...Array.from(
                         {length: TuiMonth.lengthBetween(from, to) + 1},
-                        (_, i) => months[from.append({month: i}).month],
+                        (_, i) => months[from.append({month: i}).month] ?? '',
                     ),
                     '',
                 ]),
@@ -166,7 +166,7 @@ export default class Example {
                         this.isE2E
                             ? initial
                             : Math.max(
-                                  (i ? array[i - 1][1] : initial) +
+                                  (i ? (array[i - 1]?.[1] ?? 0) : initial) +
                                       Math.random() * 10 -
                                       5,
                                   0,
diff --git a/projects/demo/src/modules/components/line-days-chart/index.ts b/projects/demo/src/modules/components/line-days-chart/index.ts
index 9de8b847b51a..f70d9b03acb9 100644
--- a/projects/demo/src/modules/components/line-days-chart/index.ts
+++ b/projects/demo/src/modules/components/line-days-chart/index.ts
@@ -24,7 +24,7 @@ export default class Page {
             .fill(0)
             .reduce<
                 ReadonlyArray<[TuiDay, number]>
-            >((array, _, i) => [...array, [new TuiDay(2020, 0, 1).append({day: i}), (i ? array[i - 1][1] : 100) + Math.random() * 20 - 10]], []),
+            >((array, _, i) => [...array, [new TuiDay(2020, 0, 1).append({day: i}), (i ? (array[i - 1]?.[1] ?? 0) : 100) + Math.random() * 20 - 10]], []),
         [
             [new TuiDay(2020, 1, 10), 10],
             [new TuiDay(2020, 1, 15), 150],
@@ -35,10 +35,10 @@ export default class Page {
         ],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 
     protected readonly labels$: Observable<readonly string[]> = this.months$.pipe(
-        map((months) => Array.from({length: 4}, (_, i) => months[i])),
+        map((months) => Array.from({length: 4}, (_, i) => months[i] ?? '')),
     );
 
     protected readonly yStringifyVariants: ReadonlyArray<TuiStringHandler<number>> = [
diff --git a/projects/demo/src/modules/components/loader/index.ts b/projects/demo/src/modules/components/loader/index.ts
index 4a66807fd1b9..5b03c6679808 100644
--- a/projects/demo/src/modules/components/loader/index.ts
+++ b/projects/demo/src/modules/components/loader/index.ts
@@ -34,7 +34,7 @@ export default class Page {
         'xxl',
     ];
 
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
 
     protected selectedTemplate = '';
 
diff --git a/projects/demo/src/modules/components/mobile-calendar/index.ts b/projects/demo/src/modules/components/mobile-calendar/index.ts
index 767554bde675..fe24b8617ebe 100644
--- a/projects/demo/src/modules/components/mobile-calendar/index.ts
+++ b/projects/demo/src/modules/components/mobile-calendar/index.ts
@@ -36,7 +36,7 @@ export default class Page {
         new TuiDay(1900, 0, 1),
     ];
 
-    protected min = this.minVariants[0];
+    protected min = this.minVariants[0]!;
 
     protected maxVariants = [
         TUI_LAST_DAY,
@@ -44,7 +44,7 @@ export default class Page {
         new TuiDay(2300, 0, 1),
     ];
 
-    protected max = this.maxVariants[0];
+    protected max = this.maxVariants[0]!;
 
     protected single = true;
     protected multi = false;
@@ -53,7 +53,7 @@ export default class Page {
         TuiBooleanHandler<TuiDay>
     > = [TUI_FALSE_HANDLER, ({day}) => day % 3 === 0];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     protected control = new FormControl<TuiDay | TuiDayRange | null>(null);
 
diff --git a/projects/demo/src/modules/components/multi-select/examples/12/index.ts b/projects/demo/src/modules/components/multi-select/examples/12/index.ts
index b2425ff5708c..37f44e37f080 100644
--- a/projects/demo/src/modules/components/multi-select/examples/12/index.ts
+++ b/projects/demo/src/modules/components/multi-select/examples/12/index.ts
@@ -42,5 +42,8 @@ export default class Example {
 
     public readonly moreOptions: readonly string[] = ['Item #6', 'Item #7', 'Item #8'];
 
-    public value: readonly string[] = [this.mainOptions[2], this.moreOptions[1]];
+    public value: readonly string[] = [
+        this.mainOptions[2] ?? '',
+        this.moreOptions[1] ?? '',
+    ];
 }
diff --git a/projects/demo/src/modules/components/multi-select/examples/5/index.ts b/projects/demo/src/modules/components/multi-select/examples/5/index.ts
index 6a2d3f1a2c78..c22162301d81 100644
--- a/projects/demo/src/modules/components/multi-select/examples/5/index.ts
+++ b/projects/demo/src/modules/components/multi-select/examples/5/index.ts
@@ -30,5 +30,5 @@ export default class Example {
 
     protected readonly sith: readonly string[] = ['Emperor', 'Darth Vader', 'Darth Maul'];
 
-    protected value: readonly string[] = [this.jedi[0]];
+    protected value: readonly string[] = [this.jedi[0] ?? ''];
 }
diff --git a/projects/demo/src/modules/components/multi-select/examples/6/index.ts b/projects/demo/src/modules/components/multi-select/examples/6/index.ts
index 7ab840abcf43..da1e1163acc7 100644
--- a/projects/demo/src/modules/components/multi-select/examples/6/index.ts
+++ b/projects/demo/src/modules/components/multi-select/examples/6/index.ts
@@ -30,5 +30,5 @@ export default class Example {
         'مایکل پیلین',
     ];
 
-    protected value: readonly string[] = [this.items[0]];
+    protected value: readonly string[] = [this.items[0] ?? ''];
 }
diff --git a/projects/demo/src/modules/components/multi-select/index.ts b/projects/demo/src/modules/components/multi-select/index.ts
index 3f1cf5ae2f59..ef21c189a3ca 100644
--- a/projects/demo/src/modules/components/multi-select/index.ts
+++ b/projects/demo/src/modules/components/multi-select/index.ts
@@ -86,14 +86,14 @@ export default class PageComponent extends AbstractExampleTuiControl {
         (item) => String(String(item).match(/\d+/)),
     ];
 
-    protected stringify = this.stringifyVariants[0];
+    protected stringify = this.stringifyVariants[0]!;
 
     protected identityMatcherVariants: ReadonlyArray<TuiIdentityMatcher<Account>> = [
         (item1, item2) => item1 === item2,
         (item1, item2) => item1.balance === item2.balance,
     ];
 
-    protected identityMatcher = this.identityMatcherVariants[0];
+    protected identityMatcher = this.identityMatcherVariants[0]!;
 
     protected tagValidatorVariants: ReadonlyArray<TuiBooleanHandler<Account>> = [
         TUI_TRUE_HANDLER,
@@ -101,7 +101,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         (item) => !item.name.startsWith('Pounds'),
     ];
 
-    protected tagValidator = this.tagValidatorVariants[0];
+    protected tagValidator = this.tagValidatorVariants[0]!;
 
     protected readonly valueContentVariants: ReadonlyArray<
         PolymorpheusContent<TuiContext<readonly Account[]>>
@@ -113,7 +113,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         TuiBooleanHandler<Account>
     > = [TUI_FALSE_HANDLER, (item: Account) => item.balance < 300];
 
-    protected disabledItemHandler = this.disabledItemHandlerVariants[0];
+    protected disabledItemHandler = this.disabledItemHandlerVariants[0]!;
 
     public control = new FormControl<Account[] | null>(null);
 
@@ -126,7 +126,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
     ];
 
     public override size: TuiSizeL | TuiSizeS =
-        this.sizeVariants[this.sizeVariants.length - 1];
+        this.sizeVariants[this.sizeVariants.length - 1]!;
 
     public override readonly maxLengthVariants: readonly number[] = [10];
 
diff --git a/projects/demo/src/modules/components/pagination/index.ts b/projects/demo/src/modules/components/pagination/index.ts
index 97b94316b788..3a22b245449e 100644
--- a/projects/demo/src/modules/components/pagination/index.ts
+++ b/projects/demo/src/modules/components/pagination/index.ts
@@ -15,7 +15,7 @@ export default class Page {
     protected index = 0;
     protected length = 8;
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
     protected activePadding = 1;
     protected sidePadding = 1;
 }
diff --git a/projects/demo/src/modules/components/pie-chart/examples/2/index.html b/projects/demo/src/modules/components/pie-chart/examples/2/index.html
index 1916cf78cac3..af54e457b51f 100644
--- a/projects/demo/src/modules/components/pie-chart/examples/2/index.html
+++ b/projects/demo/src/modules/components/pie-chart/examples/2/index.html
@@ -7,6 +7,6 @@
     #content
     let-index
 >
-    <span>{{ value[index] | tuiAmount: 'RUB' | async }}</span>
+    <span>{{ value[index] || 0 | tuiAmount: 'RUB' | async }}</span>
     <div>{{ labels[index] }}</div>
 </ng-template>
diff --git a/projects/demo/src/modules/components/pie-chart/index.ts b/projects/demo/src/modules/components/pie-chart/index.ts
index e2ea5ae442ac..d9101bebc956 100644
--- a/projects/demo/src/modules/components/pie-chart/index.ts
+++ b/projects/demo/src/modules/components/pie-chart/index.ts
@@ -25,11 +25,11 @@ export default class Page {
         [13769, 12367, 10172, 3018, 2592],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 
     protected readonly activeItemIndexVariants = [NaN, 0, 1, 2];
 
-    protected activeItemIndex = this.activeItemIndexVariants[0];
+    protected activeItemIndex = this.activeItemIndexVariants[0]!;
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeXL | TuiSizeXS> = [
         'xs',
@@ -39,7 +39,7 @@ export default class Page {
         'xl',
     ];
 
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
 
     protected readonly contentVariants: ReadonlyArray<
         PolymorpheusContent<TuiContext<number>>
@@ -49,14 +49,14 @@ export default class Page {
         ({$implicit}) => this.format($implicit),
     ];
 
-    protected hintContent = this.contentVariants[0];
+    protected hintContent = this.contentVariants[0]!;
 
     protected getPercent(index: number): string {
-        return `${tuiRound((100 * this.value[index]) / tuiSum(...this.value), 2)} %`;
+        return `${tuiRound((100 * (this.value[index] ?? 0)) / tuiSum(...this.value), 2)} %`;
     }
 
     protected format(index: number): string {
-        return `${tuiFormatNumber(this.value[index])} ${tuiGetCurrencySymbol(
+        return `${tuiFormatNumber(this.value[index] ?? 0)} ${tuiGetCurrencySymbol(
             TuiCurrency.Ruble,
         )}`;
     }
diff --git a/projects/demo/src/modules/components/primitive-textfield/index.ts b/projects/demo/src/modules/components/primitive-textfield/index.ts
index 42fe2afd4771..7ca0a22a6c38 100644
--- a/projects/demo/src/modules/components/primitive-textfield/index.ts
+++ b/projects/demo/src/modules/components/primitive-textfield/index.ts
@@ -51,10 +51,10 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
 
     protected readonly routes = DemoRoute;
     protected readonly themes = ['Taiga UI', 'Bootstrap', 'Material'];
-    protected theme = this.themes[0];
+    protected theme = this.themes[0]!;
 
     protected readonly iconVariants = ['', '@tui.search', 'Interactive content'];
-    protected selectedIcon = this.iconVariants[0];
+    protected selectedIcon = this.iconVariants[0]!;
 
     protected readonly iconLeftVariants = ['', '@tui.pie-chart', '@tui.credit-card'];
 
@@ -84,7 +84,7 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
 
     protected readonly inputModeVariants: readonly string[] = ['text', 'numeric'];
 
-    protected inputMode = this.inputModeVariants[0];
+    protected inputMode = this.inputModeVariants[0]!;
 
     protected readonly customContentVariants = [
         '',
@@ -92,7 +92,7 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
         '<span>LongTextContent</span>',
     ];
 
-    protected customContentSelected = this.customContentVariants[0];
+    protected customContentSelected = this.customContentVariants[0]!;
 
     protected password = '';
 
@@ -110,7 +110,7 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
 
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
 
     protected readonly hintContentVariants: readonly string[] = ['', 'Ivan Ivanov'];
 
@@ -120,11 +120,11 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
 
     protected invalid = false;
 
-    protected hintContent = this.hintContentVariants[0];
+    protected hintContent = this.hintContentVariants[0]!;
 
-    protected hintDirection = this.hintDirectionVariants[0];
+    protected hintDirection = this.hintDirectionVariants[0]!;
 
-    protected hintAppearance = this.hintAppearanceVariants[0];
+    protected hintAppearance = this.hintAppearanceVariants[0]!;
 
     protected get customContent(): string | null {
         return this.customContentSelected;
@@ -145,7 +145,7 @@ export default class PageComponent extends AbstractExampleTuiInteractive {
     }
 
     protected get isMaterial(): boolean {
-        return this.theme === this.themes[2];
+        return this.theme === this.themes[2]!;
     }
 
     protected get placeholder(): string {
diff --git a/projects/demo/src/modules/components/progress-bar/index.ts b/projects/demo/src/modules/components/progress-bar/index.ts
index f693bccb33c5..146e1c6c479e 100644
--- a/projects/demo/src/modules/components/progress-bar/index.ts
+++ b/projects/demo/src/modules/components/progress-bar/index.ts
@@ -25,7 +25,7 @@ export default class Page {
         'xxl',
     ];
 
-    protected size: TuiSizeXS | TuiSizeXXL = this.sizeVariants[2];
+    protected size: TuiSizeXS | TuiSizeXXL = this.sizeVariants[2]!;
 
     protected readonly colorVariants: readonly string[] = [
         'var(--tui-background-accent-1)',
@@ -35,5 +35,5 @@ export default class Page {
         'linear-gradient(to right, var(--tui-chart-categorical-02), var(--tui-chart-categorical-14), var(--tui-chart-categorical-12))',
     ];
 
-    protected color = this.colorVariants[0];
+    protected color = this.colorVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/progress-circle/index.ts b/projects/demo/src/modules/components/progress-circle/index.ts
index 5f79a76985e7..7ad00010bb7b 100644
--- a/projects/demo/src/modules/components/progress-circle/index.ts
+++ b/projects/demo/src/modules/components/progress-circle/index.ts
@@ -38,5 +38,5 @@ export default class Page {
         'url(#gradient)',
     ];
 
-    protected color = this.colorVariants[0];
+    protected color = this.colorVariants[0]!;
 }
diff --git a/projects/demo/src/modules/components/push/index.ts b/projects/demo/src/modules/components/push/index.ts
index b2f1a7ba3fbc..9f9ac54a33a9 100644
--- a/projects/demo/src/modules/components/push/index.ts
+++ b/projects/demo/src/modules/components/push/index.ts
@@ -18,6 +18,6 @@ export default class Page {
     protected type = '';
 
     protected readonly timestampVars = ['', 'A moment ago', 123456789];
-    protected timestamp = this.timestampVars[0];
+    protected timestamp = this.timestampVars[0]!;
     protected readonly routes = DemoRoute;
 }
diff --git a/projects/demo/src/modules/components/radio/examples/3/index.ts b/projects/demo/src/modules/components/radio/examples/3/index.ts
index 06752c35e4a6..43541ea13ebd 100644
--- a/projects/demo/src/modules/components/radio/examples/3/index.ts
+++ b/projects/demo/src/modules/components/radio/examples/3/index.ts
@@ -41,8 +41,8 @@ export default class Example {
 
     protected readonly strings = ['King Arthur', "It's Man", 'Silly Walks'];
 
-    protected horizontal = this.strings[0];
+    protected horizontal = this.strings[0]!;
 
     protected readonly handler: TuiBooleanHandler<string> = (item) =>
-        item === this.strings[2];
+        item === this.strings[2]!;
 }
diff --git a/projects/demo/src/modules/components/range/index.ts b/projects/demo/src/modules/components/range/index.ts
index 38ee74fe34c4..9829c69469de 100644
--- a/projects/demo/src/modules/components/range/index.ts
+++ b/projects/demo/src/modules/components/range/index.ts
@@ -17,7 +17,7 @@ export default class Page {
 
     protected readonly sizeVariants: readonly TuiSizeS[] = ['s', 'm'];
 
-    protected size: TuiSizeS = this.sizeVariants[1];
+    protected size: TuiSizeS = this.sizeVariants[1]!;
 
     protected min = 0;
 
diff --git a/projects/demo/src/modules/components/ring-chart/examples/2/index.ts b/projects/demo/src/modules/components/ring-chart/examples/2/index.ts
index 095cf1652278..6ac9e7442647 100644
--- a/projects/demo/src/modules/components/ring-chart/examples/2/index.ts
+++ b/projects/demo/src/modules/components/ring-chart/examples/2/index.ts
@@ -22,10 +22,10 @@ export default class Example {
     protected index = NaN;
 
     protected get sum(): number {
-        return Number.isNaN(this.index) ? this.total : this.value[this.index];
+        return (Number.isNaN(this.index) ? this.total : this.value[this.index]) ?? 0;
     }
 
     protected get label(): string {
-        return Number.isNaN(this.index) ? 'Total' : this.labels[this.index];
+        return (Number.isNaN(this.index) ? 'Total' : this.labels[this.index]) ?? '';
     }
 }
diff --git a/projects/demo/src/modules/components/ring-chart/index.ts b/projects/demo/src/modules/components/ring-chart/index.ts
index d744ad7ad620..085f0c7a8a0b 100644
--- a/projects/demo/src/modules/components/ring-chart/index.ts
+++ b/projects/demo/src/modules/components/ring-chart/index.ts
@@ -17,11 +17,11 @@ export default class Page {
         [13769, 10172, 3018, 2592],
     ];
 
-    protected value = this.valueVariants[0];
+    protected value = this.valueVariants[0]!;
 
     protected readonly activeItemIndexVariants = [NaN, 0, 1, 2];
 
-    protected activeItemIndex = this.activeItemIndexVariants[0];
+    protected activeItemIndex = this.activeItemIndexVariants[0]!;
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeXL | TuiSizeXS> = [
         'xs',
@@ -31,5 +31,5 @@ export default class Page {
         'xl',
     ];
 
-    protected size = this.sizeVariants[2];
+    protected size = this.sizeVariants[2]!;
 }
diff --git a/projects/demo/src/modules/components/select/examples/4/index.ts b/projects/demo/src/modules/components/select/examples/4/index.ts
index a5c91044f558..134e44c0d35f 100644
--- a/projects/demo/src/modules/components/select/examples/4/index.ts
+++ b/projects/demo/src/modules/components/select/examples/4/index.ts
@@ -23,7 +23,7 @@ export default class Example {
         ...inject<readonly string[]>('Pythons' as any),
     ];
 
-    protected value = this.pythons[0];
+    protected value = this.pythons[0]!;
 
     protected addMore(select: TuiSelectComponent<unknown>): void {
         select.handleOption(select.value);
diff --git a/projects/demo/src/modules/components/select/index.ts b/projects/demo/src/modules/components/select/index.ts
index 8e590333a372..e2ec914c20e0 100644
--- a/projects/demo/src/modules/components/select/index.ts
+++ b/projects/demo/src/modules/components/select/index.ts
@@ -68,7 +68,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
 
     protected readonly valueTemplateVariants = ['', 'Template'];
 
-    protected selectedValueTemplate = this.valueTemplateVariants[0];
+    protected selectedValueTemplate = this.valueTemplateVariants[0]!;
 
     protected readonly identityMatcherVariants: ReadonlyArray<
         TuiIdentityMatcher<Account>
@@ -77,7 +77,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
         (item1, item2) => item1.balance === item2.balance,
     ];
 
-    protected identityMatcher = this.identityMatcherVariants[0];
+    protected identityMatcher = this.identityMatcherVariants[0]!;
 
     protected readonly disabledItemHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<Account>
@@ -85,7 +85,7 @@ export default class PageComponent extends AbstractExampleTuiControl {
 
     public readonly iconVariants = ['', '@tui.pie-chart', '@tui.credit-card'];
 
-    public override iconStart = this.iconVariants[0];
+    public override iconStart = this.iconVariants[0]!;
 
     public control = new FormControl<Account | null>(null, Validators.required);
 
diff --git a/projects/demo/src/modules/components/sheet/examples/6/index.html b/projects/demo/src/modules/components/sheet/examples/6/index.html
index 050759a1d548..cd67aacf4443 100644
--- a/projects/demo/src/modules/components/sheet/examples/6/index.html
+++ b/projects/demo/src/modules/components/sheet/examples/6/index.html
@@ -19,7 +19,7 @@ <h2 tuiSheetHeading>
             alt=""
             class="image"
             [src]="image"
-            (waIntersectionObservee)="onIntersection($event, img)"
+            (waIntersectionObservee)="$event[0] && onIntersection($event[0], img)"
         />
     </ng-container>
 </ng-template>
diff --git a/projects/demo/src/modules/components/sheet/examples/6/index.ts b/projects/demo/src/modules/components/sheet/examples/6/index.ts
index df847c0462fc..11ddce0e4445 100644
--- a/projects/demo/src/modules/components/sheet/examples/6/index.ts
+++ b/projects/demo/src/modules/components/sheet/examples/6/index.ts
@@ -36,7 +36,7 @@ export default class Example {
     }
 
     protected onIntersection(
-        [{isIntersecting}]: IntersectionObserverEntry[],
+        {isIntersecting}: IntersectionObserverEntry,
         {classList}: HTMLElement,
     ): void {
         classList.toggle('_visible', isIntersecting);
diff --git a/projects/demo/src/modules/components/slider/index.ts b/projects/demo/src/modules/components/slider/index.ts
index e778adbd8a70..2407974fd5f6 100644
--- a/projects/demo/src/modules/components/slider/index.ts
+++ b/projects/demo/src/modules/components/slider/index.ts
@@ -17,7 +17,7 @@ export default class Page {
     protected max = 5;
     protected min = 0;
     protected step = 1;
-    protected size: TuiSizeS = this.sizeVariants[1];
+    protected size: TuiSizeS = this.sizeVariants[1]!;
     protected segments = this.max;
 
     protected get disabled(): boolean {
diff --git a/projects/demo/src/modules/components/stepper/index.ts b/projects/demo/src/modules/components/stepper/index.ts
index 84f9b47ba82e..d613a0c61e07 100644
--- a/projects/demo/src/modules/components/stepper/index.ts
+++ b/projects/demo/src/modules/components/stepper/index.ts
@@ -25,11 +25,11 @@ export default class Page {
         'vertical',
     ];
 
-    protected orientation: TuiOrientation = this.orientationVariants[0];
+    protected orientation: TuiOrientation = this.orientationVariants[0]!;
 
     protected readonly iconVariants = ['', '@tui.clock', '@tui.heart'];
 
-    protected icon = this.iconVariants[0];
+    protected icon = this.iconVariants[0]!;
 
     protected readonly stateVariants = ['normal', 'pass', 'error'] as const;
 
diff --git a/projects/demo/src/modules/components/table-pagination/index.ts b/projects/demo/src/modules/components/table-pagination/index.ts
index 64f435830eee..358bcae20497 100644
--- a/projects/demo/src/modules/components/table-pagination/index.ts
+++ b/projects/demo/src/modules/components/table-pagination/index.ts
@@ -20,8 +20,8 @@ export default class Page {
 
     protected total = 1000;
     protected page = 5;
-    protected items = this.itemsVariants[0];
-    protected size = this.items[0];
+    protected items = this.itemsVariants[0]!;
+    protected size = this.items[0]!;
 
     protected update({page, size}: TuiTablePaginationEvent): void {
         this.page = page;
diff --git a/projects/demo/src/modules/components/table/examples/3/index.ts b/projects/demo/src/modules/components/table/examples/3/index.ts
index 0c7ef318b79f..4f12ca4700f8 100644
--- a/projects/demo/src/modules/components/table/examples/3/index.ts
+++ b/projects/demo/src/modules/components/table/examples/3/index.ts
@@ -60,21 +60,21 @@ export default class Example {
             name: 'Holy Grail',
             price: 999999,
             quantity: 1,
-            unit: this.units[0],
+            unit: this.units[0] ?? '',
             date: TuiDay.currentLocal(),
         },
         {
             name: 'Foot',
             price: 29.95,
             quantity: 5,
-            unit: this.units[2],
+            unit: this.units[2] ?? '',
             date: TuiDay.currentLocal().append({day: -42}),
         },
         {
             name: 'Shed',
             price: 499,
             quantity: 2,
-            unit: this.units[0],
+            unit: this.units[0] ?? '',
             date: TuiDay.currentLocal().append({day: -237}),
         },
     ];
@@ -84,21 +84,21 @@ export default class Example {
             name: 'Lightsaber',
             price: 4999,
             quantity: 3,
-            unit: this.units[0],
+            unit: this.units[0] ?? '',
             date: TuiDay.currentLocal(),
         },
         {
             name: 'Spaceship',
             price: 19999,
             quantity: 1,
-            unit: this.units[0],
+            unit: this.units[0] ?? '',
             date: TuiDay.currentLocal().append({day: -237}),
         },
         {
             name: 'Stormtrooper helmet',
             price: 14.95,
             quantity: 5,
-            unit: this.units[0],
+            unit: this.units[0] ?? '',
             date: TuiDay.currentLocal().append({day: -42}),
         },
     ];
diff --git a/projects/demo/src/modules/components/table/examples/4/index.ts b/projects/demo/src/modules/components/table/examples/4/index.ts
index c6ecea474350..3b7ac145844a 100644
--- a/projects/demo/src/modules/components/table/examples/4/index.ts
+++ b/projects/demo/src/modules/components/table/examples/4/index.ts
@@ -174,7 +174,7 @@ export default class Example {
         this.enabled = enabled;
         this.columns = this.initial
             .filter((column) => enabled.includes(column))
-            .map((column) => KEYS[column]);
+            .map((column) => KEYS[column] ?? '');
     }
 
     protected onDirection(direction: -1 | 1): void {
diff --git a/projects/demo/src/modules/components/table/examples/6/index.ts b/projects/demo/src/modules/components/table/examples/6/index.ts
index be3e3ad9b607..123f3ae18731 100644
--- a/projects/demo/src/modules/components/table/examples/6/index.ts
+++ b/projects/demo/src/modules/components/table/examples/6/index.ts
@@ -18,7 +18,7 @@ export default class Example {
     protected data: Array<Record<string, number | string>> = [{id: 1, name: 'name'}];
 
     protected get columns(): string[] {
-        return Object.keys(this.data[0]);
+        return Object.keys(this.data[0] ?? {});
     }
 
     protected addColumn(): void {
diff --git a/projects/demo/src/modules/components/tabs/index.ts b/projects/demo/src/modules/components/tabs/index.ts
index 1a5402dab04e..1908fba11e99 100644
--- a/projects/demo/src/modules/components/tabs/index.ts
+++ b/projects/demo/src/modules/components/tabs/index.ts
@@ -17,7 +17,7 @@ export default class Page {
 
     protected readonly moreContentVariants = ['', 'And more'];
 
-    protected moreContent = this.moreContentVariants[0];
+    protected moreContent = this.moreContentVariants[0]!;
 
     protected underline = true;
 
@@ -27,5 +27,5 @@ export default class Page {
 
     protected sizes: readonly TuiSizeL[] = ['m', 'l'];
 
-    protected size = this.sizes[1];
+    protected size = this.sizes[1]!;
 }
diff --git a/projects/demo/src/modules/components/tag/index.ts b/projects/demo/src/modules/components/tag/index.ts
index 4ba9e77efc73..d62da6ddc1af 100644
--- a/projects/demo/src/modules/components/tag/index.ts
+++ b/projects/demo/src/modules/components/tag/index.ts
@@ -47,11 +47,11 @@ export default class Page {
         'warning',
     ];
 
-    protected status = this.statusVariants[0];
+    protected status = this.statusVariants[0]!;
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
 
-    protected size: TuiSizeL | TuiSizeS = this.sizeVariants[1];
+    protected size: TuiSizeL | TuiSizeS = this.sizeVariants[1]!;
 
     protected readonly leftContentVariants = ['', 'Error icon'];
 
diff --git a/projects/demo/src/modules/components/textarea/index.ts b/projects/demo/src/modules/components/textarea/index.ts
index 3fda953fe63e..14fcbe3cf0f2 100644
--- a/projects/demo/src/modules/components/textarea/index.ts
+++ b/projects/demo/src/modules/components/textarea/index.ts
@@ -37,9 +37,9 @@ import {InheritedDocumentation} from '../abstract/inherited-documentation';
 export default class PageComponent extends AbstractExampleTuiControl {
     protected readonly routes = DemoRoute;
     protected readonly iconVariants = ['', '@tui.search', '@tui.calendar'];
-    protected icon = this.iconVariants[0];
+    protected icon = this.iconVariants[0]!;
     protected readonly rowsVariants: readonly number[] = [8, 15, 30];
-    protected rows: number = this.rowsVariants[0];
+    protected rows: number = this.rowsVariants[0]!;
     protected expandable = false;
     protected placeholder = 'Placeholder';
 
@@ -52,5 +52,5 @@ export default class PageComponent extends AbstractExampleTuiControl {
         'l',
     ];
 
-    public override size: TuiSizeL | TuiSizeM = this.sizeVariants[1];
+    public override size: TuiSizeL | TuiSizeM = this.sizeVariants[1]!;
 }
diff --git a/projects/demo/src/modules/components/thumbnail-card/index.ts b/projects/demo/src/modules/components/thumbnail-card/index.ts
index 1d8b2ed89d38..c32710c9d020 100644
--- a/projects/demo/src/modules/components/thumbnail-card/index.ts
+++ b/projects/demo/src/modules/components/thumbnail-card/index.ts
@@ -16,8 +16,8 @@ import type {TuiSizeL, TuiSizeS} from '@taiga-ui/core';
 export default class Example {
     protected readonly examples = ['Sizes', 'A cool one', 'Backgrounds'];
     protected readonly iconVariants = ['', '@tui.lock', '@tui.cloud', '@tui.user'];
-    protected iconStart = this.iconVariants[0];
-    protected iconEnd = this.iconVariants[0];
+    protected iconStart = this.iconVariants[0]!;
+    protected iconEnd = this.iconVariants[0]!;
 
     protected readonly paymentSystemVariants: readonly TuiPaymentSystem[] = [
         'amex',
@@ -37,13 +37,13 @@ export default class Example {
     ];
 
     protected readonly sizeVariants: ReadonlyArray<TuiSizeL | TuiSizeS> = ['s', 'm', 'l'];
-    protected size = this.sizeVariants[1];
+    protected size = this.sizeVariants[1]!;
 
     protected readonly monoHandlerVariants: ReadonlyArray<
         TuiBooleanHandler<TuiPaymentSystem>
     > = [(ps) => ps === 'mir' || ps === 'visa' || ps === 'electron', TUI_TRUE_HANDLER];
 
-    protected monoHandler = this.monoHandlerVariants[0];
+    protected monoHandler = this.monoHandlerVariants[0]!;
 
     protected paymentSystem: TuiPaymentSystem | null = null;
 }
diff --git a/projects/demo/src/modules/components/tree/examples/4/index.ts b/projects/demo/src/modules/components/tree/examples/4/index.ts
index c609727ff628..d55f5f8ae8d3 100644
--- a/projects/demo/src/modules/components/tree/examples/4/index.ts
+++ b/projects/demo/src/modules/components/tree/examples/4/index.ts
@@ -54,7 +54,10 @@ export default class Example {
 
     protected toggleLevel(index: number): void {
         const nodes: readonly TreeNode[] = this.data.children || [];
+        const key = nodes[index];
 
-        this.map.set(nodes[index], !this.map.get(nodes[index]));
+        if (key) {
+            this.map.set(key, !this.map.get(key));
+        }
     }
 }
diff --git a/projects/demo/src/modules/components/tree/examples/6/index.ts b/projects/demo/src/modules/components/tree/examples/6/index.ts
index 9c74749f7050..887ea64acd9b 100644
--- a/projects/demo/src/modules/components/tree/examples/6/index.ts
+++ b/projects/demo/src/modules/components/tree/examples/6/index.ts
@@ -60,8 +60,13 @@ export default class Example {
         item: TreeNode,
         map: Map<TreeNode, boolean>,
     ): boolean | null => {
+        let result: boolean | null = null;
         const flat = flatten(item);
-        const result = !!map.get(flat[0]);
+        const key = flat[0]!;
+
+        if (key) {
+            result = !!map.get(key);
+        }
 
         for (const item of flat) {
             if (result !== !!map.get(item)) {
diff --git a/projects/demo/src/modules/directives/appearance/index.ts b/projects/demo/src/modules/directives/appearance/index.ts
index d35bdfa42cb4..1cbb099e0d24 100644
--- a/projects/demo/src/modules/directives/appearance/index.ts
+++ b/projects/demo/src/modules/directives/appearance/index.ts
@@ -12,7 +12,7 @@ import {TuiButton} from '@taiga-ui/core';
 })
 export default class Page {
     protected appearances = ['primary', 'secondary', 'flat'];
-    protected appearance = this.appearances[0];
+    protected appearance = this.appearances[0]!;
 
     protected states: readonly TuiInteractiveState[] = ['hover', 'active', 'disabled'];
     protected state: TuiInteractiveState | null = null;
diff --git a/projects/demo/src/modules/directives/dropdown-open/examples/3/index.ts b/projects/demo/src/modules/directives/dropdown-open/examples/3/index.ts
index a468044311ee..4e2f50b999bd 100644
--- a/projects/demo/src/modules/directives/dropdown-open/examples/3/index.ts
+++ b/projects/demo/src/modules/directives/dropdown-open/examples/3/index.ts
@@ -26,20 +26,20 @@ export default class Example {
     protected ascending = false;
 
     protected onClick(item: string): void {
-        if (this.items[0].includes(item)) {
+        if (this.items[0]?.includes(item)) {
             this.primary = item;
 
             return;
         }
 
-        this.ascending = item === this.items[1][0];
+        this.ascending = item === this.items[1]?.[0];
     }
 
     protected itemIsActive(item: string): boolean {
         return (
             item === this.primary ||
-            (this.ascending && item === this.items[1][0]) ||
-            (!this.ascending && item === this.items[1][1])
+            (this.ascending && item === this.items[1]?.[0]) ||
+            (!this.ascending && item === this.items[1]?.[1])
         );
     }
 }
diff --git a/projects/demo/src/modules/directives/dropdown-open/examples/4/index.ts b/projects/demo/src/modules/directives/dropdown-open/examples/4/index.ts
index 487d8d6f2e3b..890b6e6560d3 100644
--- a/projects/demo/src/modules/directives/dropdown-open/examples/4/index.ts
+++ b/projects/demo/src/modules/directives/dropdown-open/examples/4/index.ts
@@ -38,7 +38,7 @@ export default class Example {
             case 0:
                 return 'Select';
             case 1:
-                return this.value[0];
+                return this.value[0] ?? '';
             default:
                 return `${this.length} selected`;
         }
diff --git a/projects/demo/src/modules/directives/dropdown-open/index.ts b/projects/demo/src/modules/directives/dropdown-open/index.ts
index 5b56dce68c65..37fc969ed4c5 100644
--- a/projects/demo/src/modules/directives/dropdown-open/index.ts
+++ b/projects/demo/src/modules/directives/dropdown-open/index.ts
@@ -38,11 +38,11 @@ export default class PageComponent extends AbstractExampleTuiDropdown {
 
     protected enabledVariants = [true, 'getter this.input.length > 2'];
 
-    protected enabledSelected = this.enabledVariants[0];
+    protected enabledSelected = this.enabledVariants[0]!;
 
     protected readonly contentVariants = ['Template', 'Custom string'];
 
-    protected content = this.contentVariants[0];
+    protected content = this.contentVariants[0]!;
 
     protected get template(): boolean {
         return this.content === 'Template';
diff --git a/projects/demo/src/modules/directives/fluid-typography/examples/3/index.ts b/projects/demo/src/modules/directives/fluid-typography/examples/3/index.ts
index 880793680d45..8cd89e07bb60 100644
--- a/projects/demo/src/modules/directives/fluid-typography/examples/3/index.ts
+++ b/projects/demo/src/modules/directives/fluid-typography/examples/3/index.ts
@@ -19,7 +19,7 @@ export default class Example {
     protected value = 'I am a very long value';
     protected range = signal([this.options.min * 16, this.options.max * 16]);
     protected scale = computed<[number, number]>(() => [
-        this.range()[0] / 16,
-        this.range()[1] / 16,
+        (this.range()[0] ?? 0) / 16,
+        (this.range()[1] ?? 0) / 16,
     ]);
 }
diff --git a/projects/demo/src/modules/directives/media/index.ts b/projects/demo/src/modules/directives/media/index.ts
index 6729392916db..6493dca2b46b 100644
--- a/projects/demo/src/modules/directives/media/index.ts
+++ b/projects/demo/src/modules/directives/media/index.ts
@@ -14,6 +14,6 @@ export default class Page {
 
     protected playbackRate = 1;
     protected currentTime = 0;
-    protected volume = this.volumeVariants[0];
+    protected volume = this.volumeVariants[0]!;
     protected paused = true;
 }
diff --git a/projects/demo/src/modules/directives/pan/examples/1/index.ts b/projects/demo/src/modules/directives/pan/examples/1/index.ts
index 9a4ebec5e270..a62c6e7f4800 100644
--- a/projects/demo/src/modules/directives/pan/examples/1/index.ts
+++ b/projects/demo/src/modules/directives/pan/examples/1/index.ts
@@ -33,8 +33,8 @@ export default class Example {
 
     protected onPan(delta: readonly [number, number]): void {
         this.coordinates$.next([
-            this.currentCoords[0] + delta[0],
-            this.currentCoords[1] + delta[1],
+            (this.currentCoords[0] ?? 0) + delta[0],
+            (this.currentCoords[1] ?? 0) + delta[1],
         ]);
     }
 }
diff --git a/projects/demo/src/modules/directives/progress-segmented/index.ts b/projects/demo/src/modules/directives/progress-segmented/index.ts
index ab69614c6aa8..e32f6ba56c01 100644
--- a/projects/demo/src/modules/directives/progress-segmented/index.ts
+++ b/projects/demo/src/modules/directives/progress-segmented/index.ts
@@ -29,7 +29,7 @@ export default class Page {
         'xxl',
     ];
 
-    protected size: TuiProgressBar['size'] = this.sizeVariants[2];
+    protected size: TuiProgressBar['size'] = this.sizeVariants[2]!;
 
     protected readonly colorsVariants: readonly string[][] = [
         ['var(--tui-background-accent-1)'],
@@ -39,7 +39,7 @@ export default class Page {
             .map((_, index) => `var(--tui-chart-categorical-0${index + 1})`),
     ];
 
-    protected colors: string[] = this.colorsVariants[0];
+    protected colors: string[] = this.colorsVariants[0] ?? [];
 
     protected get computedColors(): string[] {
         return this.colors.slice(0, this.segments);
diff --git a/projects/demo/src/modules/directives/textfield-controller/index.ts b/projects/demo/src/modules/directives/textfield-controller/index.ts
index 2ad74d4fbc3b..ce2700d24b0b 100644
--- a/projects/demo/src/modules/directives/textfield-controller/index.ts
+++ b/projects/demo/src/modules/directives/textfield-controller/index.ts
@@ -34,17 +34,17 @@ export default class Page {
         'url',
     ];
 
-    protected type = this.typeVariants[0];
+    protected type = this.typeVariants[0]!;
 
     protected readonly customContentVariants = ['', 'Bell'];
 
-    protected customContentSelected = this.customContentVariants[0];
+    protected customContentSelected = this.customContentVariants[0]!;
 
     protected cleaner = false;
     protected exampleText = '';
     protected labelOutside = false;
-    protected size = this.sizeVariants[2];
-    protected inputMode = this.inputModeVariants[0];
+    protected size = this.sizeVariants[2]!;
+    protected inputMode = this.inputModeVariants[0]!;
     protected maxLength: number | null = null;
 
     protected readonly control = new FormControl('111', Validators.required);
diff --git a/projects/demo/src/modules/directives/validator/examples/1/index.html b/projects/demo/src/modules/directives/validator/examples/1/index.html
index f23069c15292..af21fc6983ae 100644
--- a/projects/demo/src/modules/directives/validator/examples/1/index.html
+++ b/projects/demo/src/modules/directives/validator/examples/1/index.html
@@ -12,7 +12,7 @@
         />
     </tui-select>
     <tui-input
-        *ngIf="type === items[0]; else phone"
+        *ngIf="type === items[0]!; else phone"
         formControlName="contact"
         [tuiValidator]="validator"
     >
diff --git a/projects/demo/src/modules/directives/validator/examples/1/index.ts b/projects/demo/src/modules/directives/validator/examples/1/index.ts
index bacfa23d261d..97cad387ee32 100644
--- a/projects/demo/src/modules/directives/validator/examples/1/index.ts
+++ b/projects/demo/src/modules/directives/validator/examples/1/index.ts
@@ -32,7 +32,7 @@ import {TuiInputModule, TuiInputPhoneModule, TuiSelectModule} from '@taiga-ui/le
 export default class Example {
     protected readonly items = ['Email', 'Phone'];
 
-    protected type = this.items[0];
+    protected type = this.items[0]!;
 
     protected readonly group = new FormGroup({
         name: new FormControl('', Validators.required),
diff --git a/projects/demo/src/modules/markup/breakpoints/index.ts b/projects/demo/src/modules/markup/breakpoints/index.ts
index bdae8a0ec05f..6e166a95f4bc 100644
--- a/projects/demo/src/modules/markup/breakpoints/index.ts
+++ b/projects/demo/src/modules/markup/breakpoints/index.ts
@@ -24,7 +24,7 @@ function parseBreakpoints(file: string): Array<{name: string; value: string}> {
         .map((line) => line.trim())
         .filter(Boolean)
         .map((line) => {
-            const [name, ...value] = line.split(':');
+            const [name = '', ...value] = line.split(':');
 
             return {name, value: value.join(':').replaceAll(/[~'"]/g, '').trim()};
         });
@@ -40,7 +40,7 @@ function parseBreakpoints(file: string): Array<{name: string; value: string}> {
 })
 export default class Page {
     protected readonly breakpoints = parseBreakpoints(fileWithBreakpoints);
-    protected readonly columnsNames = Object.keys(this.breakpoints[0]);
+    protected readonly columnsNames = Object.keys(this.breakpoints[0]!);
 
     protected readonly importTaigaUILocalLess = import(
         './examples/import/import-taiga-ui-local-less.md?raw'
diff --git a/projects/demo/src/modules/pipes/currency/index.html b/projects/demo/src/modules/pipes/currency/index.html
index 14779873337d..d7c8a1c83d3f 100644
--- a/projects/demo/src/modules/pipes/currency/index.html
+++ b/projects/demo/src/modules/pipes/currency/index.html
@@ -32,7 +32,7 @@
                 <ng-template>
                     <tui-input-number
                         [formControl]="control"
-                        [tuiTextfieldPostfix]="currency | tuiCurrency"
+                        [tuiTextfieldPostfix]="currency || '' | tuiCurrency"
                     >
                         Type a sum
                     </tui-input-number>
diff --git a/projects/demo/src/modules/pipes/field-error/examples/4/index.ts b/projects/demo/src/modules/pipes/field-error/examples/4/index.ts
index 8e1937bbe0ac..0e19224d2a2e 100644
--- a/projects/demo/src/modules/pipes/field-error/examples/4/index.ts
+++ b/projects/demo/src/modules/pipes/field-error/examples/4/index.ts
@@ -59,7 +59,7 @@ export default class Example {
         let n = 0;
 
         while (n <= 1 && this.formData.controls[n]) {
-            this.formData.controls[n].setValidators([
+            this.formData.controls[n]?.setValidators([
                 Validators.required,
                 this.getPhoneLengthValidator(),
             ]);
diff --git a/projects/demo/src/modules/pipes/field-error/examples/5/index.ts b/projects/demo/src/modules/pipes/field-error/examples/5/index.ts
index 96b497074444..8b41718540a6 100644
--- a/projects/demo/src/modules/pipes/field-error/examples/5/index.ts
+++ b/projects/demo/src/modules/pipes/field-error/examples/5/index.ts
@@ -45,9 +45,10 @@ export default class Example {
             text: ['русский текст', Validators.required],
         });
 
-        this.form.controls['text'].setAsyncValidators(
+        this.form.controls['text']?.setAsyncValidators(
             asyncValidatorFn(inject(TUI_IS_E2E)),
         );
-        this.form.controls['text'].markAsTouched();
+
+        this.form.controls['text']?.markAsTouched();
     }
 }
diff --git a/projects/demo/src/modules/pipes/field-error/examples/6/index.html b/projects/demo/src/modules/pipes/field-error/examples/6/index.html
index a8bdb55e7453..492fb1637202 100644
--- a/projects/demo/src/modules/pipes/field-error/examples/6/index.html
+++ b/projects/demo/src/modules/pipes/field-error/examples/6/index.html
@@ -34,7 +34,7 @@
             >
                 <tui-input-number
                     tuiHintDirection="right"
-                    [formControl]="controls[i]"
+                    [formControl]="controls[i]!"
                     [tuiHint]="[] | tuiFieldErrorContent"
                     [tuiTextfieldPostfix]="'UGX' | tuiCurrency"
                 >
diff --git a/projects/kit/components/accordion/test/accordion.component.spec.ts b/projects/kit/components/accordion/test/accordion.component.spec.ts
index 8e6d7e29975f..dff27257baa0 100644
--- a/projects/kit/components/accordion/test/accordion.component.spec.ts
+++ b/projects/kit/components/accordion/test/accordion.component.spec.ts
@@ -186,10 +186,10 @@ describe('Accordion', () => {
                 TuiAccordionItemHarness,
             );
 
-            await accordionItem1.clickHeader();
+            await accordionItem1?.clickHeader();
 
-            expect(await accordionItem1.getContent()).not.toBeNull();
-            expect(await accordionItem2.getContent()).toBeNull();
+            expect(await accordionItem1?.getContent()).not.toBeNull();
+            expect(await accordionItem2?.getContent()).toBeNull();
         });
 
         it('clicking on the 2nd section opens its contents and closes the contents of the 1st', async () => {
@@ -198,12 +198,12 @@ describe('Accordion', () => {
             );
 
             await parallel(() => [
-                accordionItem1.clickHeader(),
-                accordionItem2.clickHeader(),
+                accordionItem1?.clickHeader(),
+                accordionItem2?.clickHeader(),
             ]);
 
-            expect(await accordionItem1.getContent()).toBeNull();
-            expect(await accordionItem2.getContent()).not.toBeNull();
+            expect(await accordionItem1?.getContent()).toBeNull();
+            expect(await accordionItem2?.getContent()).not.toBeNull();
         });
 
         it('when closeOthers = false, already open sections are not closed when new ones are opened', async () => {
@@ -214,12 +214,12 @@ describe('Accordion', () => {
             );
 
             await parallel(() => [
-                accordionItem1.clickHeader(),
-                accordionItem2.clickHeader(),
+                accordionItem1?.clickHeader(),
+                accordionItem2?.clickHeader(),
             ]);
 
-            expect(await accordionItem1.getContent()).not.toBeNull();
-            expect(await accordionItem2.getContent()).not.toBeNull();
+            expect(await accordionItem1?.getContent()).not.toBeNull();
+            expect(await accordionItem2?.getContent()).not.toBeNull();
         });
 
         it.skip('pressing the space bar in the input does not close the accordion', async () => {
diff --git a/projects/kit/components/calendar-range/test/calendar-range.component.spec.ts b/projects/kit/components/calendar-range/test/calendar-range.component.spec.ts
index 99ab8e5d3763..810bcb8bc093 100644
--- a/projects/kit/components/calendar-range/test/calendar-range.component.spec.ts
+++ b/projects/kit/components/calendar-range/test/calendar-range.component.spec.ts
@@ -119,15 +119,15 @@ describe('rangeCalendarComponent', () => {
 
             const items = getItems();
 
-            expect(items[1].nativeElement.contains(getCheckmark())).toBe(true);
+            expect(items[1]?.nativeElement.contains(getCheckmark())).toBe(true);
         });
 
         it('if the value does not fit any range, check the box next to "Other date..."', () => {
-            expect(getItems()[6].nativeElement.contains(getCheckmark())).toBe(true);
+            expect(getItems()[6]?.nativeElement.contains(getCheckmark())).toBe(true);
         });
 
         it('if the value does not fit the range, the range has no tick', () => {
-            expect(getItems()[5].nativeElement.contains(getCheckmark())).toBe(false);
+            expect(getItems()[5]?.nativeElement.contains(getCheckmark())).toBe(false);
         });
 
         it('interval selection takes into account min / max', () => {
@@ -139,7 +139,10 @@ describe('rangeCalendarComponent', () => {
             testComponent.min = min;
             fixture.detectChanges();
 
-            component['onItemSelect'](component.items[5]);
+            if (component.items[5]) {
+                component['onItemSelect'](component.items[5]);
+            }
+
             fixture.detectChanges();
 
             expect(
@@ -180,8 +183,8 @@ describe('rangeCalendarComponent', () => {
             const items = getItems();
 
             expect(items.length).toBe(2);
-            expect(items[0].nativeElement.textContent.trim()).toBe(title);
-            expect(items[1].nativeElement.textContent.trim()).toBe('Other date...');
+            expect(items[0]?.nativeElement.textContent.trim()).toBe(title);
+            expect(items[1]?.nativeElement.textContent.trim()).toBe('Other date...');
         });
 
         it('when redefining intervals, displays appropriate checkbox', () => {
@@ -189,7 +192,10 @@ describe('rangeCalendarComponent', () => {
             const previousMonth = today.append({month: -1});
             const title = 'New interval';
 
-            component['onItemSelect'](component.items[0]);
+            if (component.items[0]) {
+                component['onItemSelect'](component.items[0]);
+            }
+
             fixture.detectChanges();
 
             testComponent.items = [
@@ -200,10 +206,9 @@ describe('rangeCalendarComponent', () => {
 
             const items = getItems();
 
-            expect(items[0].nativeElement.textContent.trim()).toBe(title);
-
-            expect(items[0].nativeElement.contains(getCheckmark())).toBe(false);
-            expect(items[1].nativeElement.contains(getCheckmark())).toBe(true);
+            expect(items[0]?.nativeElement.textContent.trim()).toBe(title);
+            expect(items[0]?.nativeElement.contains(getCheckmark())).toBe(false);
+            expect(items[1]?.nativeElement.contains(getCheckmark())).toBe(true);
         });
 
         it('if there are ranges with same range dates, displays appropriate checkbox when switching between them', () => {
@@ -214,19 +219,25 @@ describe('rangeCalendarComponent', () => {
                 new TuiDayRangePeriod(new TuiDayRange(previousMonth, today), '1'),
                 new TuiDayRangePeriod(new TuiDayRange(previousMonth, today), '2'),
             ];
+
             fixture.detectChanges();
 
-            component['onItemSelect'](component.items[1]);
+            if (component.items[1]) {
+                component['onItemSelect'](component.items[1]);
+            }
+
             fixture.detectChanges();
 
             const items = getItems();
 
-            expect(items[0].nativeElement.contains(getCheckmark())).toBe(false);
-            expect(items[1].nativeElement.contains(getCheckmark())).toBe(true);
+            expect(items[0]?.nativeElement.contains(getCheckmark())).toBe(false);
+            expect(items[1]?.nativeElement.contains(getCheckmark())).toBe(true);
         });
 
         it('should update selectedActivePeriod after onItemSelect', () => {
-            component['onItemSelect'](component.items[1]);
+            if (component.items[1]) {
+                component['onItemSelect'](component.items[1]);
+            }
 
             expect(testComponent.component?.selectedActivePeriod?.toString()).toBe(
                 'Today',
diff --git a/projects/kit/components/filter/test/filter.component.spec.ts b/projects/kit/components/filter/test/filter.component.spec.ts
index 66749a64c846..e71e6ac35ef0 100644
--- a/projects/kit/components/filter/test/filter.component.spec.ts
+++ b/projects/kit/components/filter/test/filter.component.spec.ts
@@ -94,7 +94,10 @@ describe('Filter', () => {
         });
 
         it('set from checked items', () => {
-            component.onCheckbox(true, ARR_STRING[0]);
+            if (ARR_STRING[0]) {
+                component.onCheckbox(true, ARR_STRING[0]);
+            }
+
             fixture.detectChanges();
 
             expect(testComponent.control.value).toEqual(ARR_STRING);
diff --git a/projects/kit/components/tabs/test/tabs.component.spec.ts b/projects/kit/components/tabs/test/tabs.component.spec.ts
index 84fdf7c9cfaa..133f8affb9c1 100644
--- a/projects/kit/components/tabs/test/tabs.component.spec.ts
+++ b/projects/kit/components/tabs/test/tabs.component.spec.ts
@@ -70,7 +70,7 @@ describe('Tabs', () => {
 
             expect(firstTab).toEqual(component.tabsDirective.activeElement);
 
-            secondTab.click();
+            secondTab?.click();
             fixture.detectChanges();
 
             expect(firstTab).not.toEqual(component.tabsDirective.activeElement);
@@ -82,14 +82,14 @@ describe('Tabs', () => {
                 (tab) => tab.nativeElement as HTMLButtonElement,
             );
 
-            expect(firstTab.classList.contains('_active')).toBeTruthy();
-            expect(secondTab.classList.contains('_active')).toBeFalsy();
+            expect(firstTab?.classList.contains('_active')).toBeTruthy();
+            expect(secondTab?.classList.contains('_active')).toBeFalsy();
 
-            secondTab.click();
+            secondTab?.click();
             fixture.detectChanges();
 
-            expect(firstTab.classList.contains('_active')).toBeFalsy();
-            expect(secondTab.classList.contains('_active')).toBeTruthy();
+            expect(firstTab?.classList.contains('_active')).toBeFalsy();
+            expect(secondTab?.classList.contains('_active')).toBeTruthy();
         });
     });
 });
diff --git a/projects/legacy/components/combo-box/test/combo-box.component.spec.ts b/projects/legacy/components/combo-box/test/combo-box.component.spec.ts
index 7cdf684fa04b..7b3fa6b89993 100644
--- a/projects/legacy/components/combo-box/test/combo-box.component.spec.ts
+++ b/projects/legacy/components/combo-box/test/combo-box.component.spec.ts
@@ -136,7 +136,7 @@ describe('ComboBox', () => {
             testComponent.defaultInputs = false;
             fixture.detectChanges();
 
-            expect(getValue()!.nativeElement.textContent.trim()).toBe(ITEMS[0].trait);
+            expect(getValue()!.nativeElement.textContent.trim()).toBe(ITEMS[0]?.trait);
         });
     });
 
diff --git a/projects/legacy/components/input-date-range/test/input-date-range.component.spec.ts b/projects/legacy/components/input-date-range/test/input-date-range.component.spec.ts
index 7711bb9f2eb8..dfe25b7e132e 100644
--- a/projects/legacy/components/input-date-range/test/input-date-range.component.spec.ts
+++ b/projects/legacy/components/input-date-range/test/input-date-range.component.spec.ts
@@ -234,8 +234,14 @@ describe('InputDateRangeComponent', () => {
             expect(leftCalendar).toBeTruthy();
             expect(rightCalendar).toBeTruthy();
 
-            getCalendarCell(leftCalendar, 16)?.nativeElement?.click();
-            getCalendarCell(rightCalendar, 27)?.nativeElement?.click();
+            if (leftCalendar) {
+                getCalendarCell(leftCalendar, 16)?.nativeElement?.click();
+            }
+
+            if (rightCalendar) {
+                getCalendarCell(rightCalendar, 27)?.nativeElement?.click();
+            }
+
             fixture.detectChanges();
 
             await fixture.whenStable();
@@ -278,8 +284,13 @@ describe('InputDateRangeComponent', () => {
             expect(leftCalendar).toBeTruthy();
             expect(rightCalendar).toBeTruthy();
 
-            getCalendarCell(leftCalendar, 12)?.nativeElement?.click();
-            getCalendarCell(rightCalendar, 18)?.nativeElement?.click();
+            if (leftCalendar) {
+                getCalendarCell(leftCalendar, 12)?.nativeElement?.click();
+            }
+
+            if (rightCalendar) {
+                getCalendarCell(rightCalendar, 18)?.nativeElement?.click();
+            }
 
             fixture.detectChanges();
 
@@ -435,8 +446,13 @@ describe('InputDateRangeComponent', () => {
             expect(leftCalendar).toBeTruthy();
             expect(rightCalendar).toBeTruthy();
 
-            getCalendarCell(leftCalendar, 12)?.nativeElement?.click();
-            getCalendarCell(rightCalendar, 18)?.nativeElement?.click();
+            if (leftCalendar) {
+                getCalendarCell(leftCalendar, 12)?.nativeElement?.click();
+            }
+
+            if (rightCalendar) {
+                getCalendarCell(rightCalendar, 18)?.nativeElement?.click();
+            }
 
             fixture.detectChanges();
 
diff --git a/projects/legacy/components/input-phone/test/complete-phone-insertion-preprocessor.spec.ts b/projects/legacy/components/input-phone/test/complete-phone-insertion-preprocessor.spec.ts
index b4915308c254..0e09bd0fecfe 100644
--- a/projects/legacy/components/input-phone/test/complete-phone-insertion-preprocessor.spec.ts
+++ b/projects/legacy/components/input-phone/test/complete-phone-insertion-preprocessor.spec.ts
@@ -34,7 +34,7 @@ describe('tuiCreateCompletePhoneInsertionPreprocessor + browser autofill', () =>
 
         tests.forEach(([before, after]) => {
             it(`${before} => ${after}`, () => {
-                expect(maskitoTransform(before, maskOptions)).toBe(after);
+                expect(maskitoTransform(before ?? '', maskOptions)).toBe(after);
             });
         });
     });
@@ -63,7 +63,7 @@ describe('tuiCreateCompletePhoneInsertionPreprocessor + browser autofill', () =>
 
         tests.forEach(([before, after]) => {
             it(`${before} => ${after}`, () => {
-                expect(maskitoTransform(before, maskOptions)).toBe(after);
+                expect(maskitoTransform(before ?? '', maskOptions)).toBe(after);
             });
         });
     });
diff --git a/projects/legacy/components/input-range/test/input-range.component.spec.ts b/projects/legacy/components/input-range/test/input-range.component.spec.ts
index ee8cf3b49f67..c9356c488b15 100644
--- a/projects/legacy/components/input-range/test/input-range.component.spec.ts
+++ b/projects/legacy/components/input-range/test/input-range.component.spec.ts
@@ -202,7 +202,7 @@ describe('InputRange', () => {
                 testComponent.control.value?.[1],
             );
             expect(inputPOLeft.value).toBe(
-                `${testComponent.control.value?.[1].toString()} лет`,
+                `${testComponent.control.value?.[1]?.toString()} лет`,
             );
         });
 
@@ -217,7 +217,7 @@ describe('InputRange', () => {
             );
             expect(inputPORight.value).toBe(
                 `${testComponent.control.value?.[0]
-                    .toString()
+                    ?.toString()
                     .replace(CHAR_HYPHEN, CHAR_MINUS)} лет`,
             );
         });
diff --git a/projects/legacy/components/input-time/test/input-time.component.spec.ts b/projects/legacy/components/input-time/test/input-time.component.spec.ts
index 92fa4b26c58b..2e42b7c9731f 100644
--- a/projects/legacy/components/input-time/test/input-time.component.spec.ts
+++ b/projects/legacy/components/input-time/test/input-time.component.spec.ts
@@ -282,7 +282,7 @@ describe('InputTime', () => {
             pageObject.getByAutomationId('tui-input-time__item')!.nativeElement.click();
 
             expect(testComponent.control.value?.toString().trim()).toBe(
-                TIMES[6].toString(),
+                TIMES[6]?.toString(),
             );
         });
 
diff --git a/projects/legacy/components/input/test/input.component.spec.ts b/projects/legacy/components/input/test/input.component.spec.ts
index dfd13cdfae4d..a2915c5e24b1 100644
--- a/projects/legacy/components/input/test/input.component.spec.ts
+++ b/projects/legacy/components/input/test/input.component.spec.ts
@@ -174,7 +174,7 @@ describe('Input', () => {
                 .getByAutomationId('tui-data-list-wrapper__option')!
                 .nativeElement.click();
 
-            expect(testComponent.control.value).toBe(ITEMS[0].toString());
+            expect(testComponent.control.value).toBe(ITEMS[0]?.toString());
         });
     });
 
@@ -289,7 +289,7 @@ describe('Input', () => {
         });
 
         it('focus in the dropdown', () => {
-            expect(tuiActiveText()).toBe(ITEMS[0].toString());
+            expect(tuiActiveText()).toBe(ITEMS[0]?.toString());
         });
 
         it('entering characters brings focus to the input field', () => {
diff --git a/projects/legacy/components/multi-select/multi-select-group/multi-select-group.component.ts b/projects/legacy/components/multi-select/multi-select-group/multi-select-group.component.ts
index c521a43b359a..3a2a21624558 100644
--- a/projects/legacy/components/multi-select/multi-select-group/multi-select-group.component.ts
+++ b/projects/legacy/components/multi-select/multi-select-group/multi-select-group.component.ts
@@ -62,7 +62,7 @@ export class TuiMultiSelectGroupComponent<T> {
 
                 for (let i = 0; i < items.length; i++) {
                     const selected = current.some((selected) =>
-                        this.matcher(selected, items[i]),
+                        this.matcher(selected, items[i]!),
                     );
 
                     if ((!selected && result) || (selected && !result && i)) {
diff --git a/scripts/shared/parse-version.ts b/scripts/shared/parse-version.ts
index 7cdadca27d3d..46430e514394 100644
--- a/scripts/shared/parse-version.ts
+++ b/scripts/shared/parse-version.ts
@@ -6,7 +6,7 @@ interface ParsedVersion {
 }
 
 export function parseVersion(version: string): ParsedVersion {
-    const [major, minor, patch, , rc = -1] = version
+    const [major = 0, minor = 0, patch = 0, , rc = -1] = version
         .split(/[.-]/)
         .map((value) => Number(value));
 
diff --git a/tsconfig.json b/tsconfig.json
index 79465c5ffbfe..87f4a5e1c6a2 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,7 +4,6 @@
         "baseUrl": "./",
         "outDir": "./dist",
         "typeRoots": ["node_modules/@types"],
-        "verbatimModuleSyntax": true,
         "paths": {
             "@demo-cypress/*": ["projects/demo-cypress/cypress/*"],
             "@demo-playwright/utils": ["projects/demo-playwright/utils/index"],