In most cases, the errors are fixed by simply adding a typehint. In one case, initializing a variable with `0.` (float) instead of `0` (int) is necessary.
In the case of `raise UnicodeError`, mypy found an actual bug.
```
>>> raise UnicodeDecodeError
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: function takes exactly 5 arguments (0 given)
```
Rather than figuring out what the 5 arguments should be, it is simpler (and cleaner) to raise and catch a custom error for that particular case.
I skipped `contrib/macdeploy`, because this module has some hairy errors. It can always be linted in a separate diff in the future.
Depends on D13637