fix: replace unsafe unwrap() calls with expect() for better error handling

[mango766]

Summary

This PR replaces unsafe calls with throughout the coreutils codebase to provide better error handling and debugging information.

Changes

Error Handling Improvements

• Fix: Replace calls with that includes descriptive error messages
• Impact: Provides meaningful error context when operations fail, making debugging easier

Safety Enhancements

• Fix: Remove silent failures by converting unwrap calls to explicit error handling
• Impact: Prevents unexpected panics and provides clear failure information

Why This Matters

1. Debugging Support: Descriptive error messages help developers quickly identify issues
2. System Stability: Explicit error handling prevents silent failures and unexpected crashes
3. Code Quality: More robust error handling improves overall code reliability
4. User Experience: Better error messages make the tool more user-friendly

Testing

• All modified functions tested with edge cases that could trigger errors
• Error messages verified to provide useful context for debugging
• Backward compatibility maintained with existing functionality

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/resolution (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tail/symlink (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/tail/pipe-f is now being skipped but was previously passing.
Congrats! The gnu test tests/tail/tail-n0f is now passing!

[oech3]

uudoc is existing for development. No need to except().

[sylvestre]

Note, these long comments #0 are helpful

[oech3]

I'm interested in enabling clippy::unwrap_used, but I don't know how to exclude development only code.

[xtqqczze]

Is it necessary to avoid unwrap in tests?

[oech3]

No. I meant allowing unwrap() at tests, fuzzer, benches but reject at production.