fixup! WIP! raise if value doesn't match setter

product/CMFCategory/CategoryTool.py

@@ -651,7 +651,7 @@ class CategoryTool(BaseTool):
       elif category_list is None:
         category_list = ()
       elif isinstance(category_list, list):
-        if any([not isinstance(c, str) for c in category_list]):
+        if any([c is not None and not isinstance(c, str) for c in category_list]):
           raise TypeError('CategoryTool.setCategoryMembership only takes string(s) as value', base_category_list, category_list)
 
       if isinstance(base_category_list, str):