title: Fire multiple actions and wait for them to resolve RxJS / Redux Observables
body: <p>I have an action that I want to use to initialise my app, I want to create an epic for this action and then fire multiple other actions off the back of this, wait for them to all complete and there fire another action. I had a look at other questions and it's pretty similar to this <a href="https://stackoverflow.com/questions/50951633/redux-observable-how-to-wait-for-multiple-async-requests-then-perform-action-in/50956494">one</a></p>
  
  <p>I've tried this approach and for me, it doesn't work, it fires the <code>APP_INIT</code> action then but then fails to fire any of the other actions in the sequence. Is anyone able to help?</p>
  
  <pre><code>import { of } from 'rxjs';
  import { mergeMap, zip, concat, mapTo } from 'rxjs/operators';
  import { ofType } from 'redux-observable';
  import { firstAction, secondAction } from 'actions';
  
  export default function appInit (action$) {
    return (
      action$.pipe(
        ofType('APP_INIT'),
        mergeMap(() =&gt;
          concat(
            of(firstAction()),
            of(secondAction()),
            zip(
              action$.ofType('ACTION_ONE_COMPLETE'),
              action$.ofType('ACTION_TWO_COMPLETE')
            ).mapTo(() =&gt; console.log('complete'))
          )
        )
      )
    );
  }
  </code></pre>