Existing unread messages when joining lead to BBB-LS faulting out with an exception

[ichdasich]

Describe the bug When there are unread messages, the aria-label of the hide user list button changes from 'Users and messages toggle' to 'Users and messages toggle with unread message notification'. This leads to BBB-LS throwing exceptions in two places:

• When there is no element found when selecting the element for a click
• When hiding the element itself

To Reproduce Steps to reproduce the behavior:

1. Create a room
2. Write to the shared notes
3. Start streaming
4. See error

Pullrequest incoming.