A useful article on debugging Python. Tools improve the process, but in my experience the quickest way to identify a bug's root cause is methodically challenging your assumptions about what is happening. With deeper knowledge and gut feeling about the code you can be faster by reordering (not skipping!) your assumptions you need to investigate. Then check them based on the observed erratic behaviour.

https://www.syntaxerror.tech/syntax-error-11-debugging-python/