Reply to Chris:
Wait. Deployment? Before deploying we *run the code* at least once and then we get the errors. And I'm not sure but type checking is ok but sometimes enforcing is a better option. Why? Mypy or typecheckers have to be run manually and they are also not part of the stdlib. Enforcing can help us catch it during editing because we don't deploy before running it at least once. So we're writing our own code and we don't run it before deploying? Mypy will catch at step 2 but enforcing can help as catch at step 1.