fix errors reported by mypy

[ghost]

Found 75 errors in 23 files (checked 43 source files)

[felix-hilden]

I have no experience with mypy. So I'm not sure of the impact of trying to conform is, but I'll look into it.

[felix-hilden]

Yeah, I tested it out, but at a quick glance none of the errors were valid. Seems like a bad move. For example, all models that had a None default were errors because a none type is of course incompatible with whatever the field is supposed to be.

[ghost]

for example:
spotipy/model/user.py:12: error: Incompatible types in assignment (expression has type "None", variable has type "Followers")

I think typing.Optional should be used:
followers: Optional[Followers] = None

(and also document on what situation followers is None?)

[felix-hilden]

I created an issue of the model types. They need some work. But here are some more points of concern, just a few of the first ones, and I can't see the reason to fix them. That's just a whole lot of unnecessary type hints.

• client/browse/__init__:226 : Incompatible types in assignment (str -> int) where a simple dict is populated. seed_artists surely is and is supposed to be a string. This goes for the other assignments as well.
• client/artist:73 : Incompatible types in assignment when parsing include_groups if they are not none. Having another variable would require an else: var = None statement and even then mypy would issue an error when assigning none to a string.
• client/player : missing return statements. They are not needed, because None should be returned. Incompatible dict types in 166, which again are not valid complaints.

[ghost]

Maybe use "# type: ignore" then?
https://mypy.readthedocs.io/en/latest/common_issues.html#spurious-errors-and-locally-silencing-the-checker

[felix-hilden]

On every such line? I'm sorry, it's a no. I'm all for using a static checker to find potential flaws but the code itself shouldn't bend to a linter's will. Maybe that's just me, but what a mess.