Handle URL-encoded Turbopack client chunks when resolving source maps (#71274)
When using Turbopack, after a client-side navigation, the source map for
a client chunk might be requested using an URL-encoded pathname, e.g.
`/_next/static/chunks/%5Bproject%5D__48591b._.js` instead of
`/_next/static/chunks/[project]__48591b._.js`. When trying to look up
the source map this would fail with:
```
Failed to get source map: [Error: chunk/module is missing a sourcemap] { code: 'GenericFailure' }
```
To fix this, we're now decoding the filename.
## Test Plan
- start `pnpm next dev --turbo test/development/app-dir/source-mapping`
- go to `http://localhost:3000`
- click on "client component page" link
- open React DevTools Components view
- select `Form`
- click on `bar()` action (requires version 6.0)
- you should end up in the the `actions.ts` source file
next.js
b6fa6be4 - Handle URL-encoded Turbopack client chunks when resolving source maps (#71274)
