title: Type 'Observable<void>' is not assignable to type 'Observable<JSON>'
body: <pre><code>  getStepList(): Observable&lt;JSON&gt;  {                  
              this.headers = new Headers();
              this.headers.append('Content-Type', 'application/json; charset=utf-8');                
              let options = new RequestOptions({
                  method: RequestMethod.Post,
                  url: "FeedbackMaster.aspx/getStepList",                   
                  headers: this.headers,
                    body:{log:this.login}
              });
              return this._http.request(new Request(options)).retry(2)
              .map((response: Response)=&gt;this.extractData(response))
              .do(data =&gt; {this.temp=data, console.log('getStepList:'+ JSON.stringify(JSON.parse(this.temp.d)))})
              .catch(this.handleError);                  
      }
  
      extractData(res: Response) {
             let body = res.json();
             return body || { }; //&lt;--- not wrapped with data
       }
            handleError(error: any) {
           console.error('An error occurred', error);
            return Promise.reject(error.message || error);
     }  
  </code></pre>
  
  <p>.......................................................................................................</p>
  
  <p>Error</p>
  
  <pre><code>[ts]
   Type 'Observable&lt;void&gt;' is not assignable to type 'Observable&lt;JSON&gt;'.
   Type 'void' is not assignable to type 'JSON'.
  </code></pre>
  
  <p>What is wrong in my code?                                                                                                                       </p>