validate empty sentinel file path in NewFileRebootChecker

[Ahmad-Faraj]

NewFileRebootChecker already returns an error but never actually used it. if you pass an empty --reboot-sentinel the checker just stats "" forever and silently never reports a reboot, which is annoying to debug.

so this rejects an empty/blank path up front instead. dropped the old TODO and added a small test.

[Copilot]

Pull request overview

This pull request improves robustness of the file-based reboot sentinel checker by validating the sentinel file path early, preventing silent misconfiguration when an empty/blank --reboot-sentinel value is provided.

Changes:

• Add upfront validation in NewFileRebootChecker to reject empty/blank file paths.
• Remove the outdated TODO now that validation exists.
• Add a unit test covering empty/blank input and a valid path case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/checkers/checker.go	Adds input validation to NewFileRebootChecker to prevent empty/blank sentinel paths.
pkg/checkers/checker_test.go	Adds a unit test verifying error behavior for empty/blank paths and success for a valid path.

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[evrardjp]

let's follow copilot suggestion

[Ahmad-Faraj]

Done, trimming once and storing the trimmed path now.

[github-actions]

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[Ahmad-Faraj]

@evrardjp the trim change is in, 157fcaeb. Any chance of another look?

[evrardjp]

I have to put that into the context of the other changes, but yeah I will work on it when I can. Thanks for your contribution.

outdated

[evrardjp]

@Ahmad-Faraj we generally request for commits to be signed for your user (you can use git gpg/ssh signing, and adding those keys into your github user). This (kinda, as you could share private keys, but that's another topic) makes sure it's not someone else developing it for you (legal reasons).

If you can't I will find a solution, but this is not my favorite path.

[Ahmad-Faraj]

@evrardjp Signed now. Rebased on main with the same diff, both commits show Verified.