Error when exporting AMP config in app dir (#45228)

Errors in app-render if an exported amp config is found.

Fixes NEXT-223

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] [e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs) tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

packages/next/src/server/app-render.tsx

@@ -1373,6 +1373,12 @@ export async function renderToHTMLOrFlight(
             `The default export of notFound is not a React Component in ${segment}`
           )
         }
+
+        if (layoutOrPageMod?.config?.amp) {
+          throw new Error(
+            'AMP is not supported in the app directory. If you need to use AMP it will continue to be supported in the pages directory.'
+          )
+        }
       }
 
       // Handle dynamic segment params.

test/development/acceptance-app/unsupported-app-features.test.ts

@@ -0,0 +1,41 @@
+/* eslint-env jest */
+import { sandbox } from './helpers'
+import { createNextDescribe, FileRef } from 'e2e-utils'
+import path from 'path'
+
+createNextDescribe(
+  'Error Overlay unsupported app features',
+  {
+    files: new FileRef(path.join(__dirname, 'fixtures', 'default-template')),
+    dependencies: {
+      react: 'latest',
+      'react-dom': 'latest',
+    },
+    skipStart: true,
+  },
+  ({ next }) => {
+    it('should show error exporting AMP config in app dir', async () => {
+      const { session, cleanup } = await sandbox(next)
+
+      // Add AMP exprot
+      await session.patch(
+        'app/page.js',
+        `
+        export const config = { amp: true }
+
+        import Component from '../index'
+        export default function Page() {
+          return <Component />
+        }
+      `
+      )
+
+      await session.hasRedbox(true)
+      expect(await session.getRedboxDescription()).toInclude(
+        'AMP is not supported in the app directory. If you need to use AMP it will continue to be supported in the pages directory.'
+      )
+
+      await cleanup()
+    })
+  }
+)