Minor fix

src/ifcopenshell-python/ifcopenshell/api/group/assign_group.py

@@ -24,7 +24,7 @@ class Usecase:
     def __init__(self, file, **settings):
         self.file = file
         self.settings = {
-            "product": None,
+            "products": None,
             "group": None,
         }
         for key, value in settings.items():
@@ -37,13 +37,13 @@ class Usecase:
                 **{
                     "GlobalId": ifcopenshell.guid.new(),
                     "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
-                    "RelatedObjects": self.settings["product"],
+                    "RelatedObjects": self.settings["products"],
                     "RelatingGroup": self.settings["group"],
                 }
             )
         rel = self.settings["group"].IsGroupedBy[0]
         related_objects = set(rel.RelatedObjects) or set()
-        for obj in self.settings["product"]:
+        for obj in self.settings["products"]:
             related_objects.add(obj)
         rel.RelatedObjects = list(related_objects)
         ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": rel})

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

@@ -324,6 +324,7 @@ def get_referenced_structures(element):
     """
     if hasattr(element, "ReferencedInStructures"):
         return [r.RelatingStructure for r in element.ReferencedInStructures]
+    return []
 
 
 def get_decomposition(element):