use async dispatch in observable to avoid blocking calls

web/src/engine/Observable.ts

@@ -40,7 +40,7 @@ export class Observable<TValue, TOwner = null> implements IObservable<TValue, TO
  /**
  * Invoke all registered subscribers passing the current value and owner.
  */
- public Dispatch(): void {
+ public async Dispatch(): Promise<void> {
  for(const subscription of this.subscribers) {
  try {
  subscription(this.value, this.owner);