Warning: Illegal string offset 'messages' in Drupal\upgrade_status\ScanResultFormatter->formatResult()

I also don't know under which conditions would that array be empty, but I added a similar check in https://git.drupalcode.org/project/upgrade_status/-/commit/727d8fa0c2f32...

That said, I would not indent the whole code here, that makes it unreadable. I'd rather skip it.

Same problem exists with producing ASCII output. People at #3193120: Shows '1 problem' after rescan following info.yml file fix, but no actual problem displayed believe they ran into the same bug but with slightly different sympthoms. Do you also experience the problem with the summary table?

Actually we need to do the opposite. Rather than fixing use of incorrect data, fix the incorrect data. I found the source in the PHPStan fail handling. Duh. That means we can get rid of the existing workaround to the broken data rather than respecting the broken data. That said, we also need an update function to remove the broken data and make people gather that data again.

Crediting @theterencechan who uncovered the underlying issue in #3193120: Shows '1 problem' after rescan following info.yml file fix, but no actual problem displayed and @joachim who opened that issue.

Fix indentation.

Also I've been thinking about not dropping the whole state altogether but rather filter out the incorrect results only (or even better fix them in the update), but then I also found #3194003: Second, third, etc. twig issues overwrite the previous twig issue found which would need a rescan, so it feels best to drop the whole scan state and require rescanning.

Crediting folks from #3178702: PHPStan Failure Message Is Incorrectly Logged When The Output Is Empty which appears to be the very same issue.

I'd like to do what it takes to get out a release soon enough for the global contribution weekend in a couple days, so given nothing against, committed this. Thanks all! Please test with -dev and report any new issues found.