Fix warnings

[dplochcoder]

Summary of Changes

Fix warnings for generated source code.

Checklist

• No change is too small for a release, so pick one:
  • I have updated the package version following semantic versioning
  • There is another change actively WIP that will update the version (link issue or PR here)
  • This PR does not update user-facing code/config
  • I'm not sure how to set the version and would like the reviewer's help

[BadMagic100]

Like I mentioned in discord you should probably add a #nullable enable in the top of the generated file to make sure it behaves correctly regardless of the user's project configuration

[BadMagic100]

Rule 'SSMM0005' has a changed 'Category' or 'Severity' from the last release. Either revert the update(s) in source or add a new up-to-date entry to unshipped release file.

0004 also has this, I'll leave you to correct the metadata in whatever way you think is appropriate

FWIW I did confirm that you can fix the nullable problems more correctly by polyfilling MemberNotNullAttribute as a file class but I felt it was a bit too ugly to commit so we can leave as is

[dplochcoder]

Like I mentioned in discord you should probably add a #nullable enable in the top of the generated file to make sure it behaves correctly regardless of the user's project configuration

ModMenuGenerator already does this.