Better error handling for `useBlockNote`

[infinite-persistence]

Describe the bug
useBlockNote currently throws an error when the given initialContent is not kosher.
Handling the error is cumbersome since effects can't be called conditionally. However, it seems like an ErrorBoundary HOC can be a workaround to suppress the error.

To Reproduce
Pass a non-json value to initialContent, e.g. initialContent: "abc".
This could come from corrupted saved data.