Wrapping a state manager to allow for async actions

state-container.ts

export type StateChange<A> = A | Observable<A> | Promise<A>;

const stateChangeToObservable = <A>(result: StateChange<A>): Observable<A> => {
  if (isObservable(result)) {
    return result;
  } else if (result instanceof Promise) {
    return from(result);
  }

  return of(result);
};
                        
export class StateContainer<A, T> {
  constructor(
    private readonly dispatch: (action: A) => any, 
    public readonly value: Observable<T>\
  ) {}
  
  update(src: StateChange<A>): Observable<T> {
    const res = stateChangeToObservable(src).pipe(shareReplay(1));
    
    res.subscribe(action => {
      this.dispatch(action)
    });
    
    return res.pipe(
      switchMapTo(this.value),
      take(1)
    );
  }
}

Nothing can subscribe to this, so what is the reason for this code?

res.pipe(
      switchMapTo(this.value),
      take(1)
    );

Unless it was supposed to be returned?

Yeah was supposed to be returned. I've been writing to much rust