[stable28] fix: prevent null token

[backportbot[bot]]

Backport of #328

Warning, This backport's changes differ from the original and might be incomplete ⚠️

Todo

• [x] Review and resolve any conflicts

• [x] Amend HEAD commit to remove the line stating to skip CI

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[susnux]

I think the workflows need to be updated:

Block merges for EOL / Block merges for EOL branches (pull_request) Failing