Ensure no events are dispatched before the websocket is open

[philippjfr]

Fixes #6521

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 40.11%. Comparing base (56e3103) to head (a224fb6).

❗ Current head a224fb6 differs from pull request most recent head 2333b9d. Consider uploading reports for the commit 2333b9d to get more accurate results

Files	Patch %	Lines
panel/chat/feed.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6528       +/-   ##
===========================================
- Coverage   81.91%   40.11%   -41.81%     
===========================================
  Files         313      313               
  Lines       45926    45909       -17     
===========================================
- Hits        37622    18416    -19206     
- Misses       8304    27493    +19189     

Flag	Coverage Δ
ui-tests	40.11% <80.00%> (+2.82%)	⬆️
unitexamples-tests	?

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