Entities with WorkerVersions are unsupported in transcription display

Sentry Issue: ARKINDEX-FRONTEND-G8

TypeError: t[0].entity.source is null
  at render (./vue/Element/SourcedTranscriptionWithEntities.vue?7c7e:1:1235)
  at call (./vue/Element/SourcedTranscriptionWithEntities.vue?7c7e:1:1125)
...
(5 additional frame(s) were not displayed)