-import { bufferTime, catchError, filter, map, share, switchMap, tap } from 'rxjs/operators'
-import { Injectable } from '@angular/core'
-import { merge, Observable, of, ReplaySubject, Subject } from 'rxjs'
+import { bufferTime, catchError, filter, map, observeOn, share, switchMap, tap } from 'rxjs/operators'
+import { Injectable, NgZone } from '@angular/core'
+import { asyncScheduler, merge, Observable, of, ReplaySubject, Subject } from 'rxjs'