message: Monitoring: Fix Silence form error catch to not assume a JSON response
diff: @@ -762,7 +762,7 @@ class SilenceForm_ extends SafetyFirst<SilenceFormProps, SilenceFormState> {
  refreshPoller('silences');
  history.push(`${SilenceResource.path}/${encodeURIComponent(_.get(data, 'silenceId'))}`);
  })
  - .catch(err => this.setState({error: err.json.error}))
  + .catch(err => this.setState({error: _.get(err, 'json.error') || err.message || 'Error saving Silence'}))
  .then(() => this.setState({inProgress: false}));
  }
  /* eslint-enable no-undef */
  