Typing commands for extended nodes

[arrocke]

I extended the Link node extension to add a command openLinkModal which as it says opens a modal to edit the current link. However when I try to type the command, I get a typescript error Subsequent property declarations must have the same type.... I don't want to change the node name, or copy the extension into my source code. We've got other extensions, far more complicated that this problem applies to where those aren't going to be viable options. Anybody have ideas?

Here is the extension file:

import BaseLink from '@tiptap/extension-link'

declare module '@tiptap/core' {
  interface Commands<ReturnType> {
    link: { // The typescript is for this property here
      openLinkModal: () => ReturnType
    }
  }
}

const Link = BaseLink.extend({
  addCommands() {
    return {
      ...(this.parent ? this.parent() : {}),
      openLinkModal: () => () => {
        this.storage.onEditLink?.()
        return true
      }
    }
  }
})
export default Link