Fix ICE when '__init__' returns any other type than '()'

[Y-Nak]

fixes #307.

What was wrong?

Semantic checks missed __init__ return type.

How was it fixed?

Assert the return type is ().

• OPTIONAL: Update Spec if applicable
• Add entry to the release notes (may forgo for trivial changes)
• Clean up commit history

[cburgdorf]

Olá Yoshitomo,

thanks for the fix. Looks good 👍
Can you also add a file 323.bugfix.md to the newsfragments directory with the content being something like:

Ensure analyzer rejects code that uses return values for __init__ function

This is so that the bugfix will be mentioned in the upcoming release notes.

[Y-Nak]

Changes:

• Add a file to newsfragments
• Replace ReST with md in newsfragments/README.md

Question:
the README.md says

If the PR fixes an issue, use that number here. If there is no issue, then open up the PR first and use the PR number for the
newsfragment.

while it seems PR number is used currently even if the corresponding issue is opened.
Should I also fix this document?

[cburgdorf]

If the PR fixes an issue, use that number here. If there is no issue, then open up the PR first and use the PR number for the
newsfragment.

I think that advice is still correct even though we often use the PR number even though the issue number would be slightly preferable. It's just a minor sloppiness on our side 🙃

[Y-Nak]

Thanks for clarifying! I leave it as is then.

[cburgdorf]

Landed 🎉 Btw, I'm taking care of the failed coverage job in #325
It is unrelated to your changes.