Sounds like the issue is that you tested parallelized code as if it were serial. That'll be a problem regardless how many issues PyLint spots. Whenever I have a

Sounds like the issue is that you tested parallelized code as if it were serial. That'll be a problem regardless how many issues PyLint spots. Whenever I have async/parallel code I am paranoid about racing and deadlocks. I always test with a bit of fuzzy sleeps to tease out any issues. Also, you described two separate bugs. The first one doesn't sound like an asynchronous callback issue. It sounds like a text editor with autocomplete would have avoided the problem. Or coding in an environment that encourages frequently running the code to look at its results.