optimizePackageImports' caches index.ts files (dev and build) when they resolve to source files outside node_modules.

[threehams]

Link to the code that reproduces this issue

https://github.com/threehams/next-optimize-caching

To Reproduce

Dev caching:

1. Run npm run dev
2. Add a syntax error to ui/index.ts

Build caching:

1. Run npm run build
2. Rename ui/Button.tsx to ui/CounterButton.tsx, and update imports in ui/index.ts
3. Run npm run build again

Current vs. Expected behavior

Current:
Dev caching: The syntax error is not reported. The dev server caches the contents of index.ts file until server restart.

Build caching:

./ui/index.ts
Module not found: Can't resolve './Button'

The build caches the index.ts file permanently, and will fail until the .next directory is deleted.

Expected:
The Next.js 14.2 release notes encourage using optimizePackageImports: ['package-name'] to optimize barrel files. When these files are outside node_modules, the imports should be re-evaluated when those index.ts files have changed on disk, in both dev and production builds.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.4.0: Fri Mar 15 00:10:42 PDT 2024; root:xnu-10063.101.17~1/RELEASE_ARM64_T6000
  Available memory (MB): 32768
  Available CPU cores: 10
Binaries:
  Node: 20.10.0
  npm: 10.2.5
  Yarn: 1.22.19
  pnpm: 9.1.0
Relevant Packages:
  next: 14.2.3 // Latest available version is detected (14.2.3).
  eslint-config-next: 14.2.3
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.4.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Developer Experience, SWC

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local)

Additional context

No response