Add registering of client-side relationship properties (#5936)

app/components/WebsocketProvider.tsx

@@ -254,9 +254,7 @@ class WebsocketProvider extends React.Component<Props> {
     });
 
     this.socket.on("comments.delete", (event: WebsocketEntityDeletedEvent) => {
-      comments.inThread(event.modelId).forEach((comment) => {
-        comments.remove(comment.id);
-      });
+      comments.remove(event.modelId);
     });
 
     this.socket.on("groups.create", (event: PartialWithId<Group>) => {