message: Avoid mutating the sorted messages
diff: @@ -53,7 +53,7 @@ export default Thread.extend({
  },
  cueCard: computed('sortedMessages.@each.loadedCard', function() {
  - let sortedMessages = this.get('sortedMessages').reverse();
  + let sortedMessages = [...this.get('sortedMessages')].reverse();
  let messageWithCueCard = sortedMessages.find((message) => {
  return message.get('loadedCard.isCueCard');
  });
  