This is where I've become a staunch proponent of type hinting Python code. I've caught more subtle bugs by enabling mypy on new sections of code than by running and debugging in production. Of course, this requires adding type hints everywhere, which can a struggle for older codebases, but MonkeyType is a great way to solve that, along with diligence on adding type hints to all new code you write, giving progressively more benefits as more of the codebase is covered by type annotations.
mypy is great but I've become enamoured with pyright[1] of late. It's super fast and catches way more problems than mypy does. It also catches syntax and semantic errors as a nice aside.
