[Bug]: Can't reconnect private GitHub repositories

### Problem description

I can't connect private repos, it gets stuck at branch selection and there is a 500 error in the console from GitHub:

I was hoping I can reconnect my GitHub accunt, but because I'm using GitHub as login it's not possible - so I'm worried I might have to create a new account and lose all my projects. Is there something better I can do?

### Steps to reproduce

1. Create a new project or edit deployment in existing one
2. Try to deploy from GitHub
3. Select a private repository

### Expected behavior

Should be able to select a branch and then confirm connection

### Environment

macOS, tried in Arc (Chromium), Firefox, Safari