message: also give empty tiles a key
diff: @@ -69,7 +69,7 @@ export default class RoomGridView extends React.Component {
  roomStores = roomStores.concat(emptyTiles);
  }
  return (<main className="mx_GroupGridView">
  - { roomStores.map((roomStore) => {
  + { roomStores.map((roomStore, i) => {
  if (roomStore) {
  const isActive = roomStore === this.state.currentRoomStore;
  const tileClasses = classNames({
  @@ -83,7 +83,7 @@ export default class RoomGridView extends React.Component {
  />
  </section>);
  } else {
  - return (<section className={"mx_GroupGridView_emptyTile"} />);
  + return (<section className={"mx_GroupGridView_emptyTile"} key={`empty-${i}`} />);
  }
  }) }
  </main>);
  