Multiple BlockNote mounted editors cause flushSync errors

[RobinClowers]

Describe the bug
When multiple editors are mounted at once, they throw flushSync errors.

flushSync was called from inside a lifecycle method. React cannot flush when React is already rendering. Consider moving this call to a scheduler task or micro task.

Similar to #1513.

To Reproduce
@edwandr helpfully created this minimal example that shows the issue. Load the page and then check the browser console.

I've forked the original reproduction and updated the dependencies to react 19 and blocknote 0.31.1.

Misc

• Node version: 22.13.0
• Package manager: Bun 1.2.1
• Browser: Firefox 137
• I'm a sponsor and would appreciate if you could look into this sooner than later 💖

[YousefED]

@RobinClowers we can look into this - I thought it only occured in niche cases. As which organization are you sponsoring?

[RobinClowers]

@YousefED Thanks! I work at Poggio.

[YousefED]

Thanks @RobinClowers . Can you still reproduce it? Atm I don't get this error in the example you provided (tried chrome and firefox)

[RobinClowers]

Oh sorry about that! I didn't realize the original example was on react 18. I've forked it and updated to the latest blocknote and react 19, and I see the errors now. https://stackblitz.com/edit/github-5zwbkwwx-eoojpbaq. Thanks again for looking into this and let me know if there is anything else I can provide.