Guard against emptying IfcShapeRepresentation Items

remove_representation_item now returns early if removing the item would
leave Items empty. edit_text_literals returns early on empty attributes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/bonsai/bonsai/tool/drawing.py

@@ -857,6 +857,8 @@ class Drawing(bonsai.core.tool.Drawing):
 
     @classmethod
     def edit_text_literals(cls, obj: bpy.types.Object, literal_attributes: dict) -> None:
+        if not literal_attributes:
+            return
         assert (element := tool.Ifc.get_entity(obj))
         assert (rep := cls.get_annotation_representation(element))
         to_remove = [i for i in rep.Items if i.is_a("IfcTextLiteral")]

src/bonsai/bonsai/tool/geometry.py

@@ -1407,8 +1407,6 @@ class Geometry(bonsai.core.tool.Geometry):
         :param representation_item: item to remove.
         :param element: item's element. Is used to unmark manual booleans.
         """
-        # NOTE: we assume it's not the last representation item
-        # otherwise we probably would need to remove representation too
         # NOTE: a lot of shared code with `geometry.remove_representation`
         ifc_file = tool.Ifc.get()
         shape_aspects: list[ifcopenshell.entity_instance] = []
@@ -1467,7 +1465,10 @@ class Geometry(bonsai.core.tool.Geometry):
             cls.remove_representation_items_from_shape_aspect([representation_item], shape_aspect)
 
         if representation:
-            representation.Items = tuple(set(representation.Items) - {representation_item})
+            new_items = tuple(set(representation.Items) - {representation_item})
+            if not new_items:
+                return
+            representation.Items = new_items
         also_consider = list(consider_inverses)
         ifcopenshell.util.element.remove_deep2(ifc_file, representation_item, also_consider=also_consider)