message: Guard against null rooms in `onEventDecrypted`
  Timeline sets may have a null room, such as with the notification timeline set.
  Here we check that case when events are decrypted to avoid throw an error.
  Fixes
diff: @@ -556,6 +556,9 @@ const TimelinePanel = React.createClass({
  },
  onEventDecrypted: function(ev) {
  + // Can be null for the notification timeline, etc.
  + if (!this.props.timelineSet.room) return;
  +
  // Need to update as we don't display event tiles for events that
  // haven't yet been decrypted. The event will have just been updated
  // in place so we just need to re-render.
  