Pyright conformance #33
Description
Pyright is a static type checker for Python. It can find many kinds of programming errors that wouldn't normally be found by a test suite. I added support for Pyright in 3b143df, and it found 1067 errors and 29 warnings in PiSCAT. None of these errors are particularly severe - most of them concern corner cases that are not triggered in practice - but I thing it would be good practice to get the number of Pyright errors and warnings down to zero.
Once the number of Pyright errors and warnings is zero, I'd also like to enable Pyright as a commit hook, such that all new code has to pass Pyright before it can be committed.