method lacking a return

  public static IEnumerable<T> SelectRecursive<T>(DependencyObject involvedView, Func<T, IEnumerable<T>> selector)
        {
            int childrenCount = 0;
            Application.Current.Dispatcher.Invoke(() => { childrenCount = VisualTreeHelper.GetChildrenCount(involvedView); });

            for (var i = 0; i < childrenCount; i++)
            {
                foreach (T child in selector(involvedView).SelectRecursive(selector))
                {
                    yield return child;
                }
            }
        }