The base error handler takes a string `message` and an `Error` object. If `raise_errors` is set to `true` on the app level, this will re-throw the error to the browser. Otherwise it will send the error to `log()`. Override this method to provide custom error handling e.g logging to a server side component or displaying some feedback to the user.
function(message, original_error) {
      if (!original_error) { original_error = new Error(); }
      original_error.message = [message, original_error.message].join(' ');
      this.trigger('error', {message: original_error.message, error: original_error});
      if (this.raise_errors) {
        throw(original_error);
      } else {
        this.log(original_error.message, original_error);
      }
    }