yCursorPlugin exception when ySyncPlugin not initialized

[khrvati]

Issue

I'm using ySyncPlugin and yCursorPlugin together, to keep my editor up-to-date and to share cursor information through awareness. Sometimes, when a client is already connected to the same room and sharing their cursor position, trying to connect with a second client causes an exception

Uncaught TypeError TypeError: Cannot read properties of undefined (reading 'nodeSize')
    at relativePositionToAbsolutePosition (/Users/krunohrvatinic/ProjectRootDirName/node_modules/y-prosemirror/src/lib.js:183:63)
    at <anonymous> (/Users/krunohrvatinic/ProjectRootDirName/node_modules/y-prosemirror/src/plugins/cursor-plugin.js:101:20)
    at createDecorations (/Users/krunohrvatinic/ProjectRootDirName/node_modules/y-prosemirror/src/plugins/cursor-plugin.js:85:25)
    at init (/Users/krunohrvatinic/ProjectRootDirName/node_modules/y-prosemirror/src/plugins/cursor-plugin.js:165:16)
    at reconfigure (/Users/krunohrvatinic/ProjectRootDirName/node_modules/prosemirror-state/dist/index.js:868:81)
...

The exception happens because ystate.binding.mapping is an empty map before ySyncPlugin finishes initializing, and relativePositionToAbsolutePosition expects a full and initialized map.

Workaround

I've fixed the issue for myself by patching cursor-plugin.js

export const createDecorations = (state, awareness, awarenessFilter, createCursor, createSelection) => {
   const ystate = ySyncPluginKey.getState(state)
   const y = ystate.doc
   const decorations = []
   if (
     ystate.snapshot != null || ystate.prevSnapshot != null ||
-    ystate.binding === null
+    ystate.binding.mapping.size === 0
   ) {
     // do not render cursors while snapshot is active
     return DecorationSet.create(state.doc, [])
   }

This seems like the right thing to do because the null check will never return true. The null check was originally added in 1.1.3, when ySyncPlugin initialized binding to null. This was changed very recently in 1.2.7 - ySyncPlugin now initializes binding to new ProsemirrorBinding, so binding is never null.

Environment Information

• MacOS, happens in Safari, Firefox and Chrome
• yjs@13.6.14
• y-prosemirror@1.2.8

I'm using y-prosemirror through Remirror, but am unaffected by #155 because my app waits until Y.Doc is loaded before loading ySyncPlugin
I'm using Liveblocks as the provider.

• I'm a sponsor 💖
• This issue is a blocker for my project.

[dmonad]

Thanks! I added a fix. This will be part of the next release.

[khrvati]

@dmonad Thank you!

If you're touching this part of the code anyway, there is a similar null-check here

y-prosemirror/src/plugins/cursor-plugin.js

Line 207 in f41a3e1

if (ystate.binding == null) {

If I got the root cause right, the check is a no-op

Leaving it in won't cause problems because absolutePositionToRelativePosition has a built-in way to handle an empty map

y-prosemirror/src/lib.js

Line 82 in f41a3e1

const pNodeSize = /** @type {any} */ (mapping.get(n) || { nodeSize: 0 }).nodeSize

...but you may want to remove or change it anyway?

[mendesanna]

Hello @dmonad
I'm still having this exact issue even though I have this latest version:

TypeError: Cannot read properties of undefined (reading 'nodeSize')
    at relativePositionToAbsolutePosition (chunk-4AVB3MJ2.js?v=3879bf73:263:37)
    at chunk-4AVB3MJ2.js?v=3879bf73:1171:20
    at Map.forEach (<anonymous>)
    at createDecorations (chunk-4AVB3MJ2.js?v=3879bf73:1157:25)
    at Plugin.init (chunk-4AVB3MJ2.js?v=3879bf73:1215:14)
    at _EditorState.reconfigure (chunk-LUJVU6BP.js?v=3879bf73:2580:75)
    at Editor2.createView (chunk-XN66PWTN.js?v=3879bf73:9440:33)
    at new Editor (chunk-XN66PWTN.js?v=3879bf73:9261:10)
    at new Editor2 (@tiptap_react.js?v=411d6cd6:3312:5)
    at @tiptap_react.js?v=411d6cd6:3620:14

I'm using y-prosemirror through Tiptap and I've checked they are using the lastest version 1.2.9.
Is there something else missing here? Can anyone help me?

[nyacg]

As above, we're also using y-prosemirror through tiptap and are on 1.2.9 and still experiencing this error

[nyacg]

Any update on this?

[dmonad]

The fix is released in y-prosemirror@1.2.10. Please make sure to use the latest version and fill out the issue template when you open another ticket.