returnFiber,
              oldFiber,
              newChild,
              expirationTime,
            );
          } else {
            return null;
          }
        }
      }
      if (isArray(newChild) || getIteratorFn(newChild)) {
        if (key !== null) {
          return null;
        }
        return updateFragment(
          returnFiber,
          oldFiber,
          newChild,
          expirationTime,
          null,
        );
      }
      throwOnInvalidObjectType(returnFiber, newChild);
    }
    if (__DEV__) {
      if (typeof newChild === 'function') {
        warnOnFunctionType();
      }
    }
    return null;