Fix newline_before_return false flags

[vladimir-beloded]

newline_before_return reports false positives from time to time.

User feedback:

Anytime I do any sort of refactoring it will incorrectly flag these issues and mask the other issues I'm actually trying to clear.

It usually appears when I switch branches

[Andrew-Bekhiet]

• Reproduced the issue by switching to different branches with different dart sdk constraints in pubspec.yaml
• Tried reproducing issue with different branches with the same dart sdk, but couldn't reproduce
• Tried again with a large codebase, which reproduced the issue due to different dependencies and running flutter pub get
  • On large codebases, custom_lint rules don't update update very slowly on changing git branches, while native dart lints update normally (Due to running flutter pub get)
  • Restarting the analysis server or reloading vscode window doesn't update custom_lint rules
  • I had to completely restart vscode to get the custom_lint rules to update (which takes time because of the large codebase)
• Possibly related issues:
  • Analysis Never Completes When custom_lint Plugin Added to analysis_options.yaml invertase/dart_custom_lint#226
  • (macos) Analyzer sometimes stops responding in VSCode when mass file change events occur dart-lang/sdk#45996 (Very similar situation, but here, it only occurs with custom_lint)
  • Dart Analyzer very slow/stuck dart-lang/sdk#55281
• Tried debugging custom_lint by attaching to dart vm, but vscode gives an error along the lines of "protocol _flutter.listviews unknown method" or something, didn't dig much into it
• Turned on custom_lint logging, and dart extension instrument logging, but dart instrument logging outputs too much text that it crashes vscode due to memory

When I opened a large project in Android Studio and kept switching branches, things were much smoother. But Android Studio didn't automatically run pub get, so I tried again with vscode and turned off auto pub get, and everything went great.
When I turned auto pub get again in vscode and switched branches, I noticed that all source control views like native vscode source control and GitLens get stuck with a progress indicator, which I think is caused by watching file changes and because the switches I do have a lot of changed files.
After a while of vscode source control views not updating and dart analyzer showing stale problems, it finally worked again and custom_lint issues were updated.

There are some steps that I'm still not sure about, and I've just noticed that the difference between the 2 commits is only 3 files, so I'll try again and will send you an up to date reproducible steps

Conclusion

The issue seems to be caused by either restarting Dart VM due to running pub get (because pubspec.yaml changed), or vscode watching changes for many files (usnig inotify for example)
Therefore this is not directly related to solid_lints