fix nested blocks added using *add* not working

src/emit/content/blockDefinition.ts

@@ -1,11 +1,11 @@
+import { Acceptor } from '@pssbletrngle/pack-resolver'
 import { Id, IdInput } from '../../common/id.js'
-import CustomEmitter from '../custom.js'
 import { BlockDefinition, BlockProperties } from '../../schema/content/blockDefinition.js'
-import { ModelRules } from '../assets/models.js'
 import { BlockstateRules } from '../assets/blockstates.js'
+import { ModelRules } from '../assets/models.js'
+import CustomEmitter from '../custom.js'
 import { LootRules } from '../data/loot.js'
 import { ClearableEmitter } from '../index.js'
-import { Acceptor } from '@pssbletrngle/pack-resolver'
 
 export type BlockDefinitionOptions = Readonly<{
    blockstate?: boolean

src/emit/content/innerBlockDefinition.ts

@@ -1,15 +1,15 @@
-import { AbstractBlockDefinitionRules, BlockDefinitionRules } from './blockDefinition.js'
+import { IdInput } from '../../common/id.js'
+import { BlockDefinition } from '../../schema/content/blockDefinition.js'
+import { BlockstateRules } from '../assets/blockstates.js'
 import { ModelRules } from '../assets/models.js'
 import { LootRules } from '../data/loot.js'
-import { BlockstateRules } from '../assets/blockstates.js'
-import { BlockDefinition } from '../../schema/content/blockDefinition.js'
-import { IdInput } from '../../common/id.js'
+import { AbstractBlockDefinitionRules, BlockDefinitionRules } from './blockDefinition.js'
 
 /* eslint-disable @typescript-eslint/no-explicit-any */
 
 class InnerBlockDefinitionRules extends AbstractBlockDefinitionRules {
-   add<T extends BlockDefinition>(id: IdInput, definition: T): T {
-      return definition
+   add<T extends BlockDefinition>(id: IdInput | T, definition?: T): T {
+      return definition ?? (id as T)
    }
 }
 

src/schema/content/blockDefinition.ts

@@ -1,5 +1,5 @@
 export type BlockProperties = Readonly<{
-   material: string
+   material?: string
    strength?: number
 }>
 

test/content.test.ts

@@ -1,5 +1,5 @@
-import setupLoader from './shared/loaderSetup.js'
 import createTestAcceptor from './mock/TestAcceptor.js'
+import setupLoader from './shared/loaderSetup.js'
 
 const { loader } = setupLoader({ load: false })
 
@@ -68,4 +68,32 @@ describe('integration with content packs mod', () => {
          },
       })
    })
+
+   it('uses custom definition types for nested block', async () => {
+      const acceptor = createTestAcceptor()
+
+      loader.content.blocks.basic('example:sapphire_block', { material: 'stone', type: 'example_block' })
+      loader.content.items.basic('example:sapphire', { type: 'example' })
+      loader.content.items.blockItem('example:sapphire_ore', {
+         type: 'example_block_item',
+         block: blocks =>
+            blocks.add({
+               type: 'example_block',
+               properties: {
+                  material: 'ice',
+               },
+            }),
+      })
+
+      await loader.emit(acceptor)
+
+      expect(acceptor.jsonAt('content/example/block/sapphire_block.json')).toMatchObject({ type: 'example_block' })
+      expect(acceptor.jsonAt('content/example/item/sapphire.json')).toMatchObject({ type: 'example' })
+      expect(acceptor.jsonAt('content/example/item/sapphire_ore.json')).toMatchObject({
+         type: 'example_block_item',
+         block: {
+            type: 'example_block',
+         },
+      })
+   })
 })