Closes#9990 by collecting all paths with errors during `next export` and reporting them sorted in the error summary at the end.
It will produce an output similar to:
```
Error: Export encountered errors on following paths:
/nested/page
/page
/page-1
/page-10
/page-11
/page-12
/page-13
/page-2
/page-3
/page-4
/page-5
/page-6
/page-7
/page-8
/page-9
at _default (/app/next.js/packages/next/dist/export/index.js:19:788)
at process._tickCallback (internal/process/next_tick.js:68:7)
```
I tested the output with the `handle-export-errors` integration test suite, but I'm not sure how to gracefully test this added output.
I thought of collecting all page source files with [recursiveReaddirSync](2ba352da39/packages/next/next-server/server/lib/recursive-readdir-sync.ts) but it seems I can't import it in js test files:
```
SyntaxError: /app/next.js/packages/next/next-server/server/lib/recursive-readdir-sync.ts: Unexpected token, expected "," (11:5)
9 | */
10 | export function recursiveReadDirSync(
> 11 | dir: string,
| ^
12 | arr: string[] = [],
13 | rootDir = dir
14 | ): string[] {
```
The test itself could look like:
```js
it('Reports failing paths', async () => {
const { stderr } = await nextBuild(appDir, [], {
stdout: true,
stderr: true,
})
const pages = []
// collect pages to be ['/page', '/page-1', ... etc.]
pages.forEach(page => {
expect(stderr).toContain(page)
})
})
```
