feat: Required attributes

[thatsjonsense]

Problem: When using Tiptap, there's no way to mark a Node/Mark attribute as required. Tiptap sets default: null for every attribute, and there's no way to clear this if you want an attr to be required. This causes downstream issues - for example, ProseMirror's joinBackward command may try to create a wrapping with a node that has a required attribute, without knowing how to fill it in. ProseMirror tries to guard against this using the NodeType's hasRequiredAttrs method, but when using Tiptap it will always return false.

Solution: Add a new, optional, isRequired option on attrs. If an attr is set up with this property, and no default, then the default: null will be deleted and then ProseMirror's hasRequiredAttrs will return true.

Alternatively, I also considered allowing users to pass default: undefined, but this seemed more explicit.

Impact: Without this fix in @tiptap/core, I'm currently using an extension to hack this behavior. It's pretty hacky:

  onBeforeCreate() {
    Object.values(this.editor.schema.nodes).forEach((nodeType) => {
      // @ts-ignore - attrs is not a public method. But if it's ever changed, this won't crash.
      Object.values(nodeType.attrs || {}).forEach((attr: any) => {
        if (attr.default === undefined) {
          attr.hasDefault = false
        }
      })
    })
  },
})```

[netlify]

✅ Deploy Preview for tiptap-embed ready!

Name	Link
🔨 Latest commit	e173b3d
🔍 Latest deploy log	https://app.netlify.com/sites/tiptap-embed/deploys/623a734f4fc64d00086c0111
😎 Deploy Preview	https://deploy-preview-2640--tiptap-embed.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.