Extract ajax error message from MVC exception

_getErrorMessage.ts

private _getErrorMessage(jqXHR: JQueryXHR, textStatus, errorThrown): string {
  var message = textStatus + ' ' + errorThrown;
  var error = <any>$.parseJSON(jqXHR.responseText);
  if (error) {
     message = error.Message;

    if (error.ExceptionMessage) {
      message += error.ExceptionMessage;
    }
  }

  return message;
  }