Adding fallback extensions for unsupported node/mark types

Hi Marijn,

Thanks for quick reply.

My use case is not a straightforward one. I’m migrating my project from draft-js based editor to prosemirror. There’s a bunch of draft-js plugins that are being transformed to prosemirror extensions. Also, there’s a lot of user content in JSON format, containing these plugins data. So, I do know the final schema, but it takes time to fully implement all the extensions. I think such fallback extension could be useful during this migration period.

As you suggested, before editor instantiation the user content is being analyzed. So, I have a set of available extensions vs a set of marks/nodes that found in a specific content to be displayed. So, I’m trying to generate the fallback extensions and use the full extension set in editor.