ControlUtils: Fix FinAllChildren

Elwig/Helpers/ControlUtils.cs

@@ -58,7 +58,8 @@ namespace Elwig.Helpers {
                     continue;
                 } else if (child is T t) {
                     yield return t;
-                } else if (child is DependencyObject childDepOpj) {
+                }
+                if (child is DependencyObject childDepOpj) {
                     foreach (T childOfChild in FindAllChildren<T>(childDepOpj)) {
                         yield return childOfChild;
                     }