diff --git a/src/bonsai/bonsai/bim/module/model/workspace.py b/src/bonsai/bonsai/bim/module/model/workspace.py
index abe4f45113..8ee17667ed 100644
--- a/src/bonsai/bonsai/bim/module/model/workspace.py
+++ b/src/bonsai/bonsai/bim/module/model/workspace.py
@@ -1280,7 +1280,22 @@ class Hotkey(bpy.types.Operator, tool.Ifc.Operator):
             bpy.ops.bim.extend_profile(join_type="T")
 
         else:
-            bpy.ops.bim.extend_walls_to_underside()
+            # Extend LAYER2 walls to the underside of another selected element.
+            # Guard the selection here so an invalid combination (e.g. a column
+            # and a slab, with no wall involved) reports a clean end-user error
+            # instead of surfacing the nested operator's ERROR as a developer
+            # traceback (see #7454).
+            walls = [
+                obj
+                for obj in bpy.context.selected_objects
+                if (element := tool.Ifc.get_entity(obj)) and tool.Parametric.is_path_connectable_wall(element)
+            ]
+            if walls and len(bpy.context.selected_objects) > len(walls):
+                bpy.ops.bim.extend_walls_to_underside()
+            else:
+                self.report(
+                    {"ERROR"}, "Please select at least one LAYER2 element and at least one other IFC element"
+                )
 
     def hotkey_S_F(self):
         if not bpy.context.selected_objects: