Fix remaining type checking errors

[ahal]

#475 refactored our Pyright type checking excludes to be per line rather than ignoring entire files. Fixing these remaining errors is a good first issue!

First ensure you can run pyright locally:

$ pip install -r requirements/dev.txt
$ pyright

You should see no errors. Next:

1. Search for the string # type: ignore in the code base.
2. Remove it.
3. Run pyright and verify you see the error.
4. Figure out how to fix the error.
5. Submit a PR

Feel free to batch many fixes into one PR if you like. And no need to fix everything! This issue can be tackled a little bit at a time, possibly even by multiple contributors.

[ahal]

The change to switch to ignoring type errors line by line finally landed:
ae78c11

So the instructions in this issue make sense now.