Unknown error at connectivity check with TURN Server when user is not in "Limit to Groups" list and `turns: only` is selected

How to use GitHub

• Please use the 👍 reaction to show that you are affected by the same issue.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Steps to reproduce

1. Make sure user is not in the "Limit to Groups" list and the list is not empty
2. Check the connectivity with the TURN Server and select turns: only

This issue seems very similar to https://github.com/nextcloud/spreed/issues/9416.

Expected behaviour

Successful connection

Actual behaviour

Unknown error

Talk app

Talk app version: 18.0.3

Custom TURN server configured: yes

Custom STUN server configured: yes

Browser

Operating system: Ubuntu

Browser name: Firefox

**Browser version:**122.0 (64-bit) - based on Snap

Start by reproducing the Talk connectivity check with a custom TURN and STUN server, using turns: only and a user outside the non-empty "Limit to Groups" list. Trace the connectivity-check entry point to determine why it reports "Unknown error" instead of a successful connection, and verify the scenario succeeds after the fix.