Pass a typecheck

[Yoshanuikabundi]

Description

At the moment, BespokeFit uses type hinting widely, but cannot pass either MyPy or PyRight type checking. I think a good first step for maintainability would be to get it to pass at least one of these, and then add it as a lint.

I would like to get PyRight working, although it is probably more work, because having a working LSP is really great for work.