TypeError: Cannot read properties of undefined (reading 'parent')

[sentry-io]

I suspect oldObj isn't available. Maybe its value doesn't get relayed to other clients, in a multiple editor scenario?

---

Sentry Issue: STUDIO-GE5

TypeError: Cannot read properties of undefined (reading 'parent')
  at resourceCounts.applyMove (./shared/data/applyRemoteChanges.js:298:23)
  at ChangeDispatcher.apply (./shared/data/applyRemoteChanges.js:74:29)
  at resourceCounts.apply (./shared/data/applyRemoteChanges.js:204:18)
  at changeStream.doWrite (./shared/data/applyRemoteChanges.js:374:24)

[rtibbles]

Yeah, oldObj is always being stripped before being sent to the backend: https://github.com/learningequality/studio/blob/unstable/contentcuration/contentcuration/frontend/shared/data/serverSync.js#L25

We do store additional fields in a JSONField though, so I think it should be OK to add where needed.

[rtibbles]

Fixed in #4278