Tljh: broke /lab view while /tree still works

Hello, I’m running a the littlest jupyter hub. In trying to install extensions to get port forwarding working in tljh for getting port forwarding to work), I ended up updating/installing all the things and broke the /lab view:

My guess it might by the issue described here:

manually installed a jupyterlab extension which was linked to one of the home folders of the user. All users without admin rights had no access to the file which stopped the jupyterlab loader from starting.

But I don’t know how to diagnose that issue. Any tips/advice?
Thank you