• GitLens Version: 12.0.0
• Git Version: 2.35.1.windows.2
• VSCode Version: 1.64.2 f80445acd5a3dadef24aa209168452a3d97cc326 x64
• OS Version: Microsoft Windows [Version 10.0.19042.1526]

Steps to Reproduce:

1. Open a file that's in git
2. Go to the source panel
3. The error will appear and file history, commits, branches etc panels all stay empty.

Downgrading to the last 11.7.0 version makes this go away. No errors show in the Git or GitLens log in Debug mode.

I've included a pic on how to downgrade in the extensions window for other people who are affected, thankfully it's easy!