I spent my morning digging into google mug and came away with a fun debugging story.

While reading through their dot parse regex engine I noticed malformed escape sequences like incomplete unicode or empty character names were quietly passing through. A broad fallback rule was catching them and turning them into plain letters.

Looking deeper into the test folder I found an entire suite of error tests that had never been running in ci simply because the file name had a plural s at the end.

I renamed the test file so maven would pick it up, tightened the escape parser rules, and opened a pull request.

The lead maintainer reviewed it within hours, suggested adding a few more characters to the exclusion set to catch property edge cases, and merged the whole thing.