macOS universal build fails when using Icon Composer icon

[florianreinhart]

Preflight Checklist

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.

Issue Details

• Electron Packager Version:
  • 18.4.4
• Electron Version:
  • 38.2.2
• Operating System:
  • macOS 26.0.1
• Last Known Working Electron Packager version::
  • n/a

Expected Behavior

The universal build should not fail and produce a universal app.

Actual Behavior

Build fails in electron/universal:

 electron-universal SHA for file Contents/Resources/Assets.car does not match across builds 6d9d7ee8996982a1da6bacd49dbb54d971f879fe67638c23ac823fe545705c9c!=34ddb69fbeb84e440bc1119b3f335911b7db0e8620fca10d0318fa0c4ad6a395 +2ms
✖ Stitching darwin/x64 and darwin/arm64 into a darwin/universal package [FAILED: Expected all non-binary files to have identical SHAs when creating a universal build but "Contents/Resources/Assets.car" did not]
✖ Packaging application [FAILED: Expected all non-binary files to have identical SHAs when creating a universal build but "Contents/Resources/Assets.car" did not]

To Reproduce

Add Icon Composer file to universal Electron app

Additional Information

Also filed here electron/universal/#148