inner-closing.js

  const categoryFiltersStateStream = viewDataStream.switchMap(
    checkboxesComponent => {
      sub = checkboxesComponent.checkboxesStateStream.subscribe(
        state => console.log("INNER EMIT 2", state, sub),
        error => console.error("INNER ERROR 2", error),
        // but also closes before first emit
        () => console.log("INNER COMPLETE 2", sub)
      );
      return checkboxesComponent.checkboxesStateStream;
    }
  );

  // this only emits once
  categoryFiltersStateStream.subscribe(
    state => console.log("EMIT ", state),
    error => console.error("ERROR", error),
    () => console.log("COMPLETE")
  );

/* produces
INNER COMPLETE 2 Subscriber {closed: true, _parent: null, _parents: null, _subscriptions: null, syncErrorValue: null…}closed: truedestination: SafeSubscriberisStopped: truesyncErrorThrowable: falsesyncErrorThrown: falsesyncErrorValue: null_parent: null_parents: null_subscriptions: null__proto__: Subscription
INNER EMIT 2 (3) [Object, Object, Object] Subscriber {closed: true, _parent: null, _parents: null, _subscriptions: null, syncErrorValue: null…}
EMIT  (3) [Object, Object, Object]
*/