Fix issue related to determining the name of the parent group

Author: henrikmidtiby

manim/mobject/svg/svg_mobject.py

@@ -290,7 +290,8 @@ def get_mobjects_from(self, svg: se.SVG) -> dict[str, VGroup]:
                 vgroups[group_name] = vg
                 vgroup_names.append(group_name)
                 vgroup_stack.append(group_name)
-                parent_name = vgroup_stack[depth - 1]
+                parent_name = vgroup_stack[-2]
+                assert parent_name != group_name
                 vgroups[parent_name].add(vgroups[group_name])
 
             if isinstance(element, (se.Group, se.Use)):