function CatchObservable(source, fn) {
      this.source = source;
      this._fn = fn;
      __super__.call(this);
    }
Returns an observable sequence that terminates with an exception, using the specified scheduler to send out the single onError message.
 There is an alias to this method called 'throwError' for browsers <IE9.
@param {Mixed} error An object used for the sequence's termination.
@param {Scheduler} scheduler Scheduler to send the exceptional termination call on. If not specified, defaults to Scheduler.immediate.
@returns {Observable} The observable sequence that terminates exceptionally with the specified exception object.