React 19 support

[DawidKossowski]

The integration is incompatible with the new React 19 version causing errors in RTC and multi-root. We need to rewrite / enhance parts of the integration to keep it compatible.

[Mati365]

Comment by @Acrophost

There seems to be an issue with our multi-root integration.
After following the guide available in our documentation (https://ckeditor.com/docs/ckeditor5/latest/installation/integrations/react/react-multiroot.html) the roots are not initializing. The toolbar shows, but the only button that is available to press is undo button - it generates a bunch of errors when clicked

Screen.Recording.2024-05-06.at.16.19.15.mov

I also checked collaboration samples for React with React 19 beta. The real-time collaboration samples throw an error and stop at white screen (including real-time-collaboration-comments-outside-of-editor-for-react, real-time-collaboration-editor-multi-root-for-react and real-time-collaboration-revision-history-for-react

Uncaught TypeError: S.render is not a function
   at index.js:16:2203048
   at index.js:16:2203115
   at index.js:16:2203119

revision-history-for-react and track-changes-for-react seem to be working correctly.

[Mati365]

Context integration seems to be dead too :/

On React 16 / 18 works fine though.

[Mati365]

@dufipl Please reopen https://github.com/cksource/qa-internal/issues/424, according to call that we made few days ago with @filipsobol (and others) we will merge it after releasing new installation methods. It means that there were a lot of merge conflicts and it'll be required to test it again. At this moment please keep that issue open and do not test it, I'll let you know when to start.