This is related to how we want to handle block splitting, e.g. pressing enter in the middle of a paragraph. But more specifically to changes introduced in #347, nothing occurs when pressing enter in a text block. We could consider defaulting this to a newline via TinyMCE settings.

https://www.tinymce.com/docs/configure/content-filtering/#forced_root_block

We should also consider how this impacts inline editables (quote citation, image caption). We can control this via Editable prop if need be.