Be more accommodating when fetching properties to allow for incomplete scripts.

src/ifcopenshell-python/ifcopenshell/util/element.py

@@ -41,7 +41,7 @@ def get_quantities(quantities):
 
 def get_properties(properties):
     results = {}
-    for prop in properties:
+    for prop in properties or []:
         if prop.is_a("IfcPropertySingleValue"):
             results[prop.Name] = prop.NominalValue.wrappedValue if prop.NominalValue else None
         elif prop.is_a("IfcComplexProperty"):

src/ifcopenshell-python/test/util/test_element.py

@@ -51,6 +51,11 @@ class TestGetQuantitiesIFC4(test.bootstrap.IFC4):
 
 
 class TestGetPropertiesIFC4(test.bootstrap.IFC4):
+    def test_getting_no_properties_when_none_are_available(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="name")
+        assert ifcopenshell.util.element.get_properties(pset.HasProperties) == {}
+
     def test_getting_single_properties_from_a_list_of_properties(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="name")