dx: add pagePath info to missing component error (#66916)

### What 

Show the full `pagePath` information for missing default component app
router convention files.

Move runtime error tests from `rsc-build-errors.test.ts` to the new test
`test/development/acceptance-app/undefined-default-export.test.ts`

### Why

Previously we only log `segment` which could be `[slug]` that is not
enough useful for users to locate the bad defined component

Author: huozhi

packages/next/src/server/app-render/create-component-tree.tsx

@@ -51,6 +51,12 @@ export function createComponentTree(props: {
   )
 }
 
+function errorMissingDefaultExport(pagePath: string, convention: string) {
+  throw new Error(
+    `The default export is not a React Component in "${pagePath}/${convention}"`
+  )
+}
+
 async function createComponentTreeInternal({
   createSegmentPath,
   loaderTree: tree,
@@ -311,30 +317,22 @@ async function createComponentTreeInternal({
       (isPage || typeof Component !== 'undefined') &&
       !isValidElementType(Component)
     ) {
-      throw new Error(
-        `The default export is not a React Component in page: "${pagePath}"`
-      )
+      errorMissingDefaultExport(pagePath, 'page')
     }
 
     if (
       typeof ErrorComponent !== 'undefined' &&
       !isValidElementType(ErrorComponent)
     ) {
-      throw new Error(
-        `The default export of error is not a React Component in page: ${segment}`
-      )
+      errorMissingDefaultExport(pagePath, 'error')
     }
 
     if (typeof Loading !== 'undefined' && !isValidElementType(Loading)) {
-      throw new Error(
-        `The default export of loading is not a React Component in ${segment}`
-      )
+      errorMissingDefaultExport(pagePath, 'loading')
     }
 
     if (typeof NotFound !== 'undefined' && !isValidElementType(NotFound)) {
-      throw new Error(
-        `The default export of notFound is not a React Component in ${segment}`
-      )
+      errorMissingDefaultExport(pagePath, 'not-found')
     }
   }
 

test/development/acceptance-app/rsc-build-errors.test.ts

@@ -124,41 +124,6 @@ describe('Error overlay - RSC build errors', () => {
     await cleanup()
   })
 
-  it('should error when page component export is not valid', async () => {
-    const { session, cleanup } = await sandbox(
-      next,
-      undefined,
-      '/server-with-errors/page-export'
-    )
-
-    await next.patchFile(
-      'app/server-with-errors/page-export/page.js',
-      'export const a = 123'
-    )
-
-    await session.assertHasRedbox()
-    expect(await session.getRedboxDescription()).toInclude(
-      'The default export is not a React Component in page: "/server-with-errors/page-export"'
-    )
-
-    await cleanup()
-  })
-
-  it('should error when page component export is not valid on initial load', async () => {
-    const { session, cleanup } = await sandbox(
-      next,
-      undefined,
-      '/server-with-errors/page-export-initial-error'
-    )
-
-    await session.assertHasRedbox()
-    expect(await session.getRedboxDescription()).toInclude(
-      'The default export is not a React Component in page: "/server-with-errors/page-export-initial-error"'
-    )
-
-    await cleanup()
-  })
-
   it('should throw an error when "use client" is on the top level but after other expressions', async () => {
     const { session, cleanup } = await sandbox(
       next,

test/development/acceptance-app/undefined-default-export.test.ts

@@ -0,0 +1,90 @@
+import path from 'path'
+import { FileRef, nextTestSetup } from 'e2e-utils'
+import { sandbox } from 'development-sandbox'
+
+describe('Undefined default export', () => {
+  const { next } = nextTestSetup({
+    files: new FileRef(path.join(__dirname, 'fixtures', 'default-template')),
+  })
+
+  it('should error if page component does not have default export', async () => {
+    const { session, cleanup } = await sandbox(
+      next,
+      new Map([
+        ['app/(group)/specific-path/server/page.js', 'export const a = 123'],
+      ]),
+      '/specific-path/server'
+    )
+
+    await session.assertHasRedbox()
+    expect(await session.getRedboxDescription()).toInclude(
+      'The default export is not a React Component in "/specific-path/server/page"'
+    )
+
+    await cleanup()
+  })
+
+  it('should error if not-found component does not have default export when trigger not-found boundary', async () => {
+    const { session, cleanup } = await sandbox(
+      next,
+      new Map([
+        [
+          'app/will-not-found/page.js',
+          `
+          import { notFound } from 'next/navigation'
+          export default function Page() { notFound() }
+          `,
+        ],
+        ['app/will-not-found/not-found.js', 'export const a = 123'],
+      ]),
+      '/will-not-found'
+    )
+
+    await session.assertHasRedbox()
+    expect(await session.getRedboxDescription()).toInclude(
+      'The default export is not a React Component in "/will-not-found/not-found"'
+    )
+
+    await cleanup()
+  })
+
+  it('should error when page component export is not valid', async () => {
+    const { session, cleanup } = await sandbox(
+      next,
+      undefined,
+      '/server-with-errors/page-export'
+    )
+
+    await next.patchFile(
+      'app/server-with-errors/page-export/page.js',
+      'export const a = 123'
+    )
+
+    await session.assertHasRedbox()
+    expect(await session.getRedboxDescription()).toInclude(
+      'The default export is not a React Component in "/server-with-errors/page-export/page"'
+    )
+
+    await cleanup()
+  })
+
+  it('should error when page component export is not valid on initial load', async () => {
+    const { session, cleanup } = await sandbox(
+      next,
+      new Map([
+        [
+          'app/server-with-errors/page-export-initial-error/page.js',
+          'export const a = 123',
+        ],
+      ]),
+      '/server-with-errors/page-export-initial-error'
+    )
+
+    await session.assertHasRedbox()
+    expect(await session.getRedboxDescription()).toInclude(
+      'The default export is not a React Component in "/server-with-errors/page-export-initial-error/page"'
+    )
+
+    await cleanup()
+  })
+})