Some headings put

[mfanselmo]

Describe the bug

Hey! I noticed this weird bug that breaks the editor. For some reason, one heading got introduced with the level prop as null, which makes it a html element <hnull /> that crashes on hover.

I am not quite sure what happened for a block of that type to be added with a null level prop.

To Reproduce
Still not sure how it happened, will report back if I am able to reproduce again

Misc

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