Making groups stuck in "Validating" students

For this input file Sem-Test-Gitbull.csv (tried others in similar format), after I click "validate", it gets stuck (I've been waiting like 5min and no changes).

Note:

1. I have the Gitlab API key set-up properly because it realized that I already have others repos on the selected path, and
2. The path is correct for this group https://gitlab.ewi.tudelft.nl/cse2115/2024-2025, and
3. I have enough access rights.

Fix

This is due to an error occurring on the server side (in the JS console there will be a 500 error). When this error is encountered we should inform the user.