Fix spurious errors when using --follow-imports=normal

[Jammf]

Fixes #62

When generating diagnostics for a file while using --follow-imports=normal, mypy will emit errors that occur in both the requested file and any other files it may import. However, the extension doesn't check which file an error originates from, leading to errors from other files being incorrectly reported as being for the requested file. These changes fix that behavior by stripping out all errors originating from files other than the requested file.

Additionally, this changes the default mypy configuration to be --follow-imports=normal. This makes it more similar to the previous behavior before #52, where --follow-imports=silent (which is not supported by dmypy) was used to suppress error messages while still allowing mypy to pull in useful type information from imported files.

[Jammf]

@microsoft-github-policy-service agree

[karthiknadig]

@Jammf Seems like there is an issue with python 3.7, probably need to special case it for 3.7.

[Jammf]

It looks like there might be some issue with the .nox/tests venv that dmypy is running in? I found the following line in the testing logs, which is result.stderr from the call to dmypy (and since result.stdout is empty, no diagnostics are published, which is why the tests are failing):

{'type': 4, 'message': 'The typed_ast package is not installed.\nYou can install it with `python3 -m pip install typed-ast`.\n'}

This seems to just be an issue with 3.7, and doesn't seem to be related to the changes I made (I ran local tests against main and that also had the same errors).

That said, I'm pretty stumped on how to actually fix the tests, or even why that error is occurring in the first place. It does look like typed_ast has reached EOL (along with Python 3.7 itself), but I can't see how that would cause the tests to suddenly fail.

[karthiknadig]

I have a fix for this. Basically typed-ast reached end of life yesterday. They released a new version, that version has multiple linux *.so which breaks our bundling.

[karthiknadig]

After this is merged it will be available in the next pre-release (usually the next workday)