Fix websocket error message on Firefox

[kuba-orlik]

Should fix #1674

Summary

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
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• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's body (e.g. Fixes: #xxx[,#xxx], where "xxx" is the issue number)

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• Yes, CHANGELOG.md is also updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

[Lord-Grey]

@kuba-orlik Thanks for taking the time providing a PR!
In the meantime, I had a look at the issue and I think the overall way communicating with Kodi needs to be reworked.
Currently, for every command a new WebSocket is established rather one reused during calibration.
The current code is a 1:1 conversion from http calls to WebSocket given at http was not possible due to CORS any longer.

I already started on it and will share when ready for your feedback.

PS: In addition , it would be good opening a issue a Kodi, as it seems Kodi does not handle the WebSocket close correctly.
When I just put a simple Python server instead of Kodi, the code works.

[Lord-Grey]

Closed PR due to refactoring via #1718