Allow the type of the extensionStorage field of the Editor class to be customizable

[arnaugomez]

Description

The Editor.extensionStorage field has a type of Record<string, any>. I suggest it could be strongly typed and customizable, like the type of editor commands.

The pros would be improved TypeScript type safety. The cons would be that the extension storage is not as frequently used as the commands, and that it could make the code more complex, thus making the creation of new extensions more difficult.

I created a PR, you can see it here. Tell me if it's a good feature and what you think about it :)

Use Case

For example, we could make the characterCount extension strongly typed by adding this code

declare module '@tiptap/core' {
  interface ExtensionStorage {
    characterCount: CharacterCountStorage;
  }
}

Then, when accessing Editor.extensionStorage, it would have a type of {characterCount: CharacterCountStorage}. So the developer would have autocomplete in the code editor :)

Type

New Tiptap API