bim.assign_cost_item_quantity - to show error if no related objects were found

Just to make UI more responsive - e.g. if some objects are selected but they are not products.

src/bonsai/bonsai/bim/module/cost/operator.py

@@ -265,13 +265,18 @@ class AssignCostItemQuantity(bpy.types.Operator, tool.Ifc.Operator):
     prop_name: bpy.props.StringProperty()
 
     def _execute(self, context):
-        core.assign_cost_item_quantity(
+        result = core.assign_cost_item_quantity(
             tool.Ifc,
             tool.Cost,
             cost_item=tool.Ifc.get().by_id(self.cost_item),
             related_object_type=self.related_object_type,
             prop_name=self.prop_name,  # TODO: REVIEW PROP_NAME USABILITY
         )
+        if not result:
+            self.report(
+                {"ERROR"},
+                f"Cost item wasn't assigned - no objects of type '{self.related_object_type}' are selected.",
+            )
 
 
 class UnassignCostItemQuantity(bpy.types.Operator, tool.Ifc.Operator):

src/bonsai/bonsai/core/cost.py

@@ -160,11 +160,14 @@ def assign_cost_item_quantity(
     cost_item: ifcopenshell.entity_instance,
     related_object_type: tool.Cost.RELATED_OBJECT_TYPE,
     prop_name: str,
-) -> None:
+) -> bool:
     products = cost.get_products(related_object_type)
     if products:
         ifc.run("cost.assign_cost_item_quantity", cost_item=cost_item, products=products, prop_name=prop_name)
         cost.load_cost_item_quantity_assignments(cost_item, related_object_type=related_object_type)
+        return True
+    else:
+        return False
 
 
 def load_cost_item_quantities(cost: tool.Cost) -> None: