title: Rxjs map method return undefined
body: <p>I'm tring to learn rxjs but i'm having some problems with the map operator. Here's my code:</p>
  <pre><code>    const courses$ = http$.pipe(map(res =&gt; {res['payload']}))
  
      courses$.subscribe(
          (datas) =&gt; {console.log(datas)},
          noop,
          () =&gt; {console.log('finished')}
        )
  </code></pre>
  <p><code>createObservable()</code> is a function that i defined. It simply makes an http request to a db and return the datas in json format. I tested it out and works.
  Debbuging I saw that console logging <code>res['payload'] </code> directly in map works, but when i console log it in the observable subscribe return undefined. Here there is a picture of the structure of the dats that i recive from the db<a href="https://i.stack.imgur.com/cQ114.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cQ114.png" alt="enter image description here" /></a>. Thank u all</p>