Specifying webpack configuration in next config breaks next build

[dualdetail]

Link to the code that reproduces this issue

https://github.com/dualdetail/webpack-example

To Reproduce

npm install
npm run build

Current vs. Expected behavior

Currently, build prints webpack caching failure then stops building (this also prints in dev without issues). If you remove the webpack configuration from next.config.ts the build will process normally. I set it up so the next.config.ts file does not change the config but just returns the default which still fails.

Expected behavior is build will work with webpack configuration.

Provide environment information

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Pro
  Available memory (MB): 98051
  Available CPU cores: 32
Binaries:
  Node: 23.0.0
  npm: N/A
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.0.2-canary.8 // Latest available version is detected (15.0.2-canary.8).
  eslint-config-next: 15.0.2-canary.8
  react: 19.0.0-rc-1631855f-20241023
  react-dom: 19.0.0-rc-1631855f-20241023
  typescript: 5.6.3
Next.js Config:
  output: N/A

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

Webpack

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

next build (local)

Additional context

I have tried using both npm and pnpm without success. Also I did not get webpack.cache.PackFileCacheStrategy print out in nextjs 14.2.15.