title: Property 'throw' does not exist on type 'typeof Observable'
body: <p>Iam learning nativescript+angular for developing android and ios apps.Iam working and learning basic services of nativescript+angular.In the post method of the my project i have the error 'property 'throw' does not exist on type 'typeof Observable'.
  My Code is:</p>
  
  <pre><code>import { User } from "./user";
  import { Config } from "../config";
  import { Injectable } from "@angular/core";
  import { Observable } from "tns-core-modules/ui/page/page";
  
  @Injectable()
  export class UserService {
      constructor(private http: Http) { }
  
      register(user: User) {
          let headers = new Headers();
          headers.append("Content-Type", "application/json");
  
          return this.http.post(
              Config.apiUrl + "Users",
              JSON.stringify({
                  Username: user.email,
                  Email: user.email,
                  Password: user.password
              }),
              { headers: headers }
          )
              .catch(this.handleErrors);
  
      }
  
      handleErrors(error:Response)
      {
          console.log(JSON.stringify(error.json()));
          return Observable.throw(error);        
      }
  
  
  
  } 
  </code></pre>