title: Angular 6 & rxjs 6 - subscription returns undefined
body: <p>I am using Angular CLI 6.1.3, rxjs 6.2.2 .</p>
  
  <p>To my issue: </p>
  
  <p>I implemented a Service <code>RespSearchService</code> which is responsible for getting information from a Sharepoint.</p>
  
  <p>Following code requests a JSON from the Sharepoint:</p>
  
  <pre><code>public search(queryString: string): Observable&lt;any&gt; {
      return from(
          web.siteUsers
              .filter("substringof(\'" + queryString + "\',Email)")
              .get()
              .then(v =&gt; {
                  console.log('search', v);
              })
      );
  }
  </code></pre>
  
  <p>The above code works as expected and is logging the JSON to the console.</p>
  
  <p>My issue lies within another component where I subscribe to the <code>Observable</code>, as I did in all other cases, where it works. But somehow here it will not work. It seems like the Observable returns an empty object as the log to the console says <code>undefined</code>.</p>
  
  <pre><code>export class ClaimFormInfoComponent implements OnInit {
  
      public claim: Claim = new Claim();
      public results: any;
      queryField: FormControl = new FormControl();
      constructor(private data: DataService, private respSearch: RespSearchService) { }
  
      ngOnInit() {
          this.data.currentClaim.subscribe(claim =&gt; this.claim = claim);
  
          this.respSearch.search("chri").subscribe((response: any) =&gt; {
            this.results = response;
            console.log('results', this.results); \\-&gt; results undefined
          });
      }
  }
  </code></pre>
  
  <p>I am stuck. I have no more ideas nor can I find anything useful on the internet.</p>
  
  <p>Thanks in advance for any hint or idea!</p>