Fail action when PR is not mergeable

[roryabraham]

Hello @pascalgn 👋

Coming from this comment – this action fails silently when the pull request fails to merge. Instead, the action should exit with a non-zero exit code so that the workflow can properly handle the failure.

This PR does that by introducing a fail method which uses core.setFailed to set an error message and process.exit(1) to fail the action.

The change is covered by an automated unit test.

[roryabraham]

The circleci failures we're seeing here seem unrelated to my changes.

[AndrewGable]

The CircleCI error seems like a known error that can be fixed via a node option flag --openssl-legacy-provider, @pascalgn would you like us to fix that error in this PR or another one?

[pascalgn]

The CircleCI error should be fixed via updating the node version, could you rebase the branch?

[roryabraham]

@pascalgn thanks for the tip, that worked! 🎉

[Austio]

@pascalgn anything that I can do to help get this over the line?

[roryabraham]

@pascalgn Friendly reminder about this PR 🙂 We use this action heavily in our CI but the fact that it fails silently is a pain point we would love to resolve.

[mbiagetti]

Hi @pascalgn Any updates/idea if this feature could be shipped? Thanks!

[pascalgn]

Thanks for the PR, it's merged now! It took some more time, because I had to put this behaviour behind a new option (MERGE_ERROR_FAIL), to not break existing workflows. Thanks! 🚀