View over time causes crash before survey is finished.

[TheCynosure]

Clicking the view over time button on the analytics page for a question that was used on a past survey will crash the system if no one has answered the survey yet.

visualizeTrendData/data.labels<
src/components/SurveyAnalytics/visualizers.js:70

  67 | console.log(choice_analytics);
  68 | 
  69 | let data = {
> 70 |   labels: dates.map(date => date===analytics[currentSurveyId].expiry ? 'Current Survey' : moment(date).format('MM-DD-YYYY')),
     | ^  71 |   datasets: Object.keys(choice_analytics).map((choice, index) => ({
  72 |     label: choice,
  73 |     data: dates.slice().map(date => {