message: Fix crash on opening notification panel
  The check for pending edits needed a null guard, since the notification
  panel uses MessagePanel but is not associated with a specific room.
diff: @@ -473,7 +473,7 @@ export default class MessagePanel extends React.Component {
  }
  get _roomHasPendingEdit() {
  - return localStorage.getItem(`mx_edit_room_${this.props.room.roomId}`);
  + return this.props.room && localStorage.getItem(`mx_edit_room_${this.props.room.roomId}`);
  }
  _getEventTiles() {
  