It's a very basic GitHub notifier that sits in the status bar and gently notifies the user when there are any new notifications to the subscribed entities (like PRs, etc.).
Before the launch one should create a GitHub token and add it to the macOS Keychain as GitHub API token for notifications:
Make sure that GitHub token has access to notifications. Depending on your organisation, you may also need to allow SSO for the token.
On the badge click, the app opens your favourite browser to show pending notifications on GitHub.
To enable macOS notifications you might need to explicitly enable them in system preferences, see this:
Since this is a perfect application it does not give you a way to quit it. If you really want to stop it, you should show no mercy and kill it, for example with pkill -f gh-notifications-osx.app.
Good luck!
Use Xcode, and run Product->Run to execute, or Product->Archive to create a "release" version of the app.
You can use Window->Organizer->Archives to view all available archives.
To export an archive as a local app chose Distribute App->Copy App.
The logs should be available in the OS log as well as in file at ~/Library/Containers/gh.gh-notifications-osx/Data/Library/Logs.