message: Null guard space hierarchy
diff: @@ -475,7 +475,7 @@ const INITIAL_PAGE_SIZE = 20;
  export const useRoomHierarchy = (space: Room): {
  loading: boolean;
  - rooms: IHierarchyRoom[];
  + rooms?: IHierarchyRoom[];
  hierarchy: RoomHierarchy;
  error: Error;
  loadMore(pageSize?: number): Promise<void>;
  @@ -716,7 +716,7 @@ const SpaceHierarchy = ({
  return <RovingTabIndexProvider onKeyDown={onKeyDown} handleHomeEnd handleUpDown>
  { ({ onKeyDownHandler }) => {
  let content: JSX.Element;
  - if (loading && !rooms.length) {
  + if (loading && !rooms?.length) {
  content = <Spinner />;
  } else {
  const hasPermissions = space?.getMyMembership() === "join" &&
  