[Angular] Observable.catch error handling in Angular

import { Observable } from ‘rxjs/Observable‘;
import ‘rxjs/add/operator/map‘;
import ‘rxjs/add/operator/catch‘;
import ‘rxjs/add/observable/throw‘;

  updatePassenger(passenger: Passenger): Observable<Passenger> {
    let headers = new Headers({
      ‘Content-Type‘: ‘application/json‘
    });
    let options = new RequestOptions({
      headers: headers
    });
    return this.http
      .put(`${PASSENGER_API}/${passenger.id}`, passenger, options)
      .map((response: Response) => response.json())
      .catch((error: any) => Observable.throw(error.json()));
  }