diff --git a/db/migration/1732195571407-RemoveColorDimensionFromSlopeCharts.ts b/db/migration/1732195571407-RemoveColorDimensionFromSlopeCharts.ts
index bbd12966c7d..1750d7e2576 100644
--- a/db/migration/1732195571407-RemoveColorDimensionFromSlopeCharts.ts
+++ b/db/migration/1732195571407-RemoveColorDimensionFromSlopeCharts.ts
@@ -4,7 +4,9 @@ export class RemoveColorDimensionFromSlopeCharts1732195571407
     implements MigrationInterface
 {
     public async up(queryRunner: QueryRunner): Promise<void> {
-        // update dimensions field in chart configs
+        // remove color dimension for all slope charts
+        // the y-dimension always comes first and the color dimension second,
+        // so it's safe to keep the first dimension only
         await queryRunner.query(`
             -- sql
             UPDATE chart_configs
@@ -15,7 +17,7 @@ export class RemoveColorDimensionFromSlopeCharts1732195571407
                 chartType = 'SlopeChart'
         `)
 
-        // remove from chart_dimensions table
+        // remove the color dimension for slope charts from the chart_dimensions table
         await queryRunner.query(`
             -- sql
             DELETE cd FROM chart_dimensions cd
diff --git a/packages/@ourworldindata/core-table/src/OwidTable.ts b/packages/@ourworldindata/core-table/src/OwidTable.ts
index 34dc42551cb..c17d1e7b540 100644
--- a/packages/@ourworldindata/core-table/src/OwidTable.ts
+++ b/packages/@ourworldindata/core-table/src/OwidTable.ts
@@ -124,8 +124,8 @@ export class OwidTable extends CoreTable<OwidRow, OwidColumnDef> {
         return min(this.allTimes) as Time
     }
 
-    @imemo get maxTime(): Time {
-        return max(this.allTimes) as Time
+    @imemo get maxTime(): number | undefined {
+        return max(this.allTimes)
     }
 
     @imemo private get allTimes(): Time[] {
diff --git a/packages/@ourworldindata/grapher/src/barCharts/DiscreteBarChart.tsx b/packages/@ourworldindata/grapher/src/barCharts/DiscreteBarChart.tsx
index 144ed286209..242ddc08248 100644
--- a/packages/@ourworldindata/grapher/src/barCharts/DiscreteBarChart.tsx
+++ b/packages/@ourworldindata/grapher/src/barCharts/DiscreteBarChart.tsx
@@ -409,11 +409,14 @@ export class DiscreteBarChart
             <g id={makeIdForHumanConsumption("entity-labels")}>
                 {this.placedSeries.map((series) => {
                     return (
-                        series.label &&
-                        series.label.render(
-                            series.entityLabelX,
-                            series.barY - series.label.height / 2,
-                            { textProps: style }
+                        series.label && (
+                            <React.Fragment key={series.seriesName}>
+                                {series.label.render(
+                                    series.entityLabelX,
+                                    series.barY - series.label.height / 2,
+                                    { textProps: style }
+                                )}
+                            </React.Fragment>
                         )
                     )
                 })}
@@ -990,6 +993,7 @@ function makeProjectedDataPattern(color: string): React.ReactElement {
     const size = 7
     return (
         <pattern
+            key={color}
             id={makeProjectedDataPatternId(color)}
             patternUnits="userSpaceOnUse"
             width={size}
diff --git a/packages/@ourworldindata/grapher/src/lineCharts/LineChart.tsx b/packages/@ourworldindata/grapher/src/lineCharts/LineChart.tsx
index d48ddcdd868..6def600bb85 100644
--- a/packages/@ourworldindata/grapher/src/lineCharts/LineChart.tsx
+++ b/packages/@ourworldindata/grapher/src/lineCharts/LineChart.tsx
@@ -23,7 +23,6 @@ import {
     AxisAlign,
     Color,
     HorizontalAlign,
-    PrimitiveType,
     makeIdForHumanConsumption,
 } from "@ourworldindata/utils"
 import { computed, action, observable } from "mobx"
diff --git a/packages/@ourworldindata/grapher/src/slopeCharts/SlopeChart.tsx b/packages/@ourworldindata/grapher/src/slopeCharts/SlopeChart.tsx
index b2f3cf0f243..44720736c34 100644
--- a/packages/@ourworldindata/grapher/src/slopeCharts/SlopeChart.tsx
+++ b/packages/@ourworldindata/grapher/src/slopeCharts/SlopeChart.tsx
@@ -18,7 +18,6 @@ import {
 import { observable, computed, action } from "mobx"
 import { observer } from "mobx-react"
 import { NoDataModal } from "../noDataModal/NoDataModal"
-import { ColorScaleManager } from "../color/ColorScale"
 import {
     BASE_FONT_SIZE,
     GRAPHER_DARK_TEXT,
@@ -33,7 +32,6 @@ import {
     Time,
     SeriesStrategy,
     EntityName,
-    PrimitiveType,
     RenderMode,
 } from "@ourworldindata/types"
 import { ChartInterface } from "../chart/ChartInterface"
@@ -75,9 +73,11 @@ import {
     getSeriesName,
 } from "../lineCharts/lineChartHelpers"
 
+type SVGMouseOrTouchEvent =
+    | React.MouseEvent<SVGGElement>
+    | React.TouchEvent<SVGGElement>
+
 export interface SlopeChartManager extends ChartManager {
-    isModalOpen?: boolean
-    canChangeEntity?: boolean
     canSelectMultipleEntities?: boolean
 }
 
@@ -92,9 +92,9 @@ export class SlopeChart
         bounds?: Bounds
         manager: SlopeChartManager
     }>
-    implements ChartInterface, ColorScaleManager
+    implements ChartInterface
 {
-    base: React.RefObject<SVGGElement> = React.createRef()
+    slopeAreaRef: React.RefObject<SVGGElement> = React.createRef()
     defaultBaseColorScheme = ColorSchemeName.OwidDistinctLines
 
     @observable hoveredSeriesName?: string
@@ -166,7 +166,7 @@ export class SlopeChart
     }
 
     @computed private get isLogScale(): boolean {
-        return this.props.manager.yAxisConfig?.scaleType === ScaleType.log
+        return this.yScaleType === ScaleType.log
     }
 
     @computed private get missingDataStrategy(): MissingDataStrategy {
@@ -204,26 +204,22 @@ export class SlopeChart
         return this.xScale(this.endTime)
     }
 
-    private updateTooltipPosition(
-        event: React.MouseEvent<SVGGElement> | React.TouchEvent<SVGGElement>
-    ) {
+    private updateTooltipPosition(event: SVGMouseOrTouchEvent) {
         const ref = this.manager.base?.current
         if (ref) this.tooltipState.position = getRelativeMouse(ref, event)
     }
 
-    private detectHoveredSlope(
-        event: React.MouseEvent<SVGGElement> | React.TouchEvent<SVGGElement>
-    ) {
-        const ref = this.base.current
+    private detectHoveredSlope(event: SVGMouseOrTouchEvent) {
+        const ref = this.slopeAreaRef.current
         if (!ref) return
 
         const mouse = getRelativeMouse(ref, event)
         this.mouseFrame = requestAnimationFrame(() => {
             if (this.placedSeries.length === 0) return
 
-            const distToSlope = new Map<PlacedSlopeChartSeries, number>()
+            const distanceMap = new Map<PlacedSlopeChartSeries, number>()
             for (const series of this.placedSeries) {
-                distToSlope.set(
+                distanceMap.set(
                     series,
                     PointVector.distanceFromPointToLineSegmentSq(
                         mouse,
@@ -234,9 +230,9 @@ export class SlopeChart
             }
 
             const closestSlope = minBy(this.placedSeries, (s) =>
-                distToSlope.get(s)
-            )
-            const distanceSq = distToSlope.get(closestSlope!)!
+                distanceMap.get(s)
+            )!
+            const distanceSq = distanceMap.get(closestSlope)!
             const tolerance = 10
             const toleranceSq = tolerance * tolerance
 
@@ -506,7 +502,7 @@ export class SlopeChart
     @computed get xRange(): [number, number] {
         const lineLegendWidth = this.maxLineLegendWidth + LINE_LEGEND_PADDING
 
-        // pick a reasonable width based on an ideal aspect ratio
+        // pick a reasonable max width based on an ideal aspect ratio
         const idealAspectRatio = 0.6
         const chartAreaWidth = this.bounds.width - this.sidebarWidth
         const availableWidth =
@@ -553,7 +549,7 @@ export class SlopeChart
 
     private playIntroAnimation() {
         // Nice little intro animation
-        select(this.base.current)
+        select(this.slopeAreaRef.current)
             .select(".slopes")
             .attr("stroke-dasharray", "100%")
             .attr("stroke-dashoffset", "100%")
@@ -594,11 +590,9 @@ export class SlopeChart
     }
 
     mouseFrame?: number
-    @action.bound onMouseMove(
-        ev: React.MouseEvent<SVGGElement> | React.TouchEvent<SVGGElement>
-    ) {
-        this.updateTooltipPosition(ev)
-        this.detectHoveredSlope(ev)
+    @action.bound onMouseMove(event: SVGMouseOrTouchEvent) {
+        this.updateTooltipPosition(event)
+        this.detectHoveredSlope(event)
     }
 
     @action.bound onMouseLeave() {
@@ -771,7 +765,7 @@ export class SlopeChart
                 />
                 <g
                     id={makeIdForHumanConsumption("slopes")}
-                    ref={this.base}
+                    ref={this.slopeAreaRef}
                     onMouseMove={this.onMouseMove}
                     onTouchMove={this.onMouseMove}
                     onTouchStart={this.onMouseMove}