resource.remove_resource - fix issue removing resources in ifc2x3

src/ifcopenshell-python/ifcopenshell/api/resource/remove_resource.py

@@ -74,8 +74,9 @@ def remove_resource(file: ifcopenshell.file, resource: ifcopenshell.entity_insta
                 file.remove(inverse)
                 if history:
                     ifcopenshell.util.element.remove_deep2(file, history)
-    if settings["resource"].Usage:
+    # Usage was added in IFC4.
-        file.remove(settings["resource"].Usage)
+    if usage := getattr(settings["resource"], "Usage", None):
+        file.remove(usage)
     if settings["resource"].BaseQuantity:
         ifcopenshell.api.run(
             "resource.remove_resource_quantity",

src/ifcopenshell-python/test/api/resource/test_remove_resource.py

@@ -0,0 +1,19 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2024 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+# remove_resource tests is partially covered by test_add_resource_quantity.