title: What's the observable equivalent to `Promise.reject`
body: <p>I had this code</p>
  
  <pre><code>    return this.http.get(this.pushUrl)
          .toPromise()
          .then(response =&gt; response.json().data as PushResult[])
          .catch(this.handleError);
  </code></pre>
  
  <p>I wanted to use <code>observable</code> instead of <code>Promise</code></p>
  
  <p>how can i return the error to the calling method?</p>
  
  <p>What's the equivalent to  <code>Promise.reject</code> ?</p>
  
  <pre><code>    doSomeGet() {
          console.info("sending get request");
  
          this.http.get(this.pushUrl)
              .forEach(function (response) { console.info(response.json()); })
              .catch(this.handleError);
      }
  
      private handleError(error: any) {
          console.error('An error occurred', error);
          // return Promise.reject(error.message || error);
      }
  }
  </code></pre>
  
  <p>the calling method was:</p>
  
  <pre><code>getHeroes() {
      this.pushService
          .doSomeGet();
          // .then(pushResult =&gt; this.pushResult = pushResult)
          // .catch(error =&gt; this.error = error);
  }
  </code></pre>