message: Guard around SpaceStore onAccountData handler prevEvent
diff: @@ -748,9 +748,9 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
  }
  };
  - private onAccountData = (ev: MatrixEvent, lastEvent: MatrixEvent) => {
  + private onAccountData = (ev: MatrixEvent, prevEvent?: MatrixEvent) => {
  if (!this.allRoomsInHome && ev.getType() === EventType.Direct) {
  - const lastContent = lastEvent.getContent();
  + const lastContent = prevEvent?.getContent() ?? {};
  const content = ev.getContent();
  const diff = objectDiff<Record<string, string[]>>(lastContent, content);
  