If a column is not in stat_columns, the value must be empty.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@8160 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/ListBox.py

@@ -1324,7 +1324,10 @@ class ListBoxRenderer:
       else:
         stat_method = None
 
-      if stat_method is None:
+      if stat_method_id is None:
+        original_value = None
+        processed_value = u''
+      elif stat_method is None:
         try:
           original_value = getattr(result[0], alias)
           processed_value = original_value