Move Skeleton3D init process into post_enter_tree from enter_tree

scene/3d/skeleton_3d.cpp

@@ -289,12 +289,14 @@ void Skeleton3D::_notification(int p_what) {
 	switch (p_what) {
 		case NOTIFICATION_ENTER_TREE: {
 			_process_changed();
-			_make_dirty();
-			_make_modifiers_dirty();
-			force_update_all_dirty_bones();
 #if !defined(DISABLE_DEPRECATED) && !defined(PHYSICS_3D_DISABLED)
 			setup_simulator();
 #endif // _DISABLE_DEPRECATED && PHYSICS_3D_DISABLED
+		} break;
+		case NOTIFICATION_POST_ENTER_TREE: {
+			_make_dirty();
+			_make_modifiers_dirty();
+			force_update_all_dirty_bones();
 			update_flags |= UPDATE_FLAG_POSE;
 			_notification(NOTIFICATION_UPDATE_SKELETON);
 		} break;