`wlib-formatting` check fails on aarch64-darwin with permission denied for new directories

[TrustworthyAdult]

When a PR adds files to a new directory, the checks.aarch64-darwin.wlib-formatting check fails on macOS CI with:

nixfmt: .../wrapperModules/g/ghostty: openTempFileWithDefaultPermissions: permission denied (Permission denied)

The failure happens on the directory itself, not on any .nix file. Notably, the output also shows:

formatted 0 files (0 changed)

So the files are correctly formatted -- nixfmt is crashing before it finishes, seemingly because it tries to write a temp file into the source directory, which is read-only in the Nix
store on macOS.

PR: #546
CI run: https://github.com/BirdeeHub/nix-wrapper-modules/actions/runs/26132265543

PRs that only modify existing files appear unaffected (likely due to caching), but any PR that introduces a new directory seems to trigger a fresh nixfmt run that hits this crash.

Happy to provide any additional info. Let me know if there's a workaround in the meantime.

[BirdeeHub]

Closing this now that the PR was merged.

The message is better now, regardless if the file was new or not.