Check delivery is not None before calling a getProperty on it

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@7180 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/InvoiceTransactionRule.py

@@ -141,6 +141,7 @@ class InvoiceTransactionRule(Rule, PredicateMatrix):
               while resource is None and \
                           simulation_movement != portal_simulation :
                 delivery = simulation_movement.getDeliveryValue()
+                if delivery is not None:
                   resource = delivery.getProperty('price_currency', None)
                 if simulation_movement.getParentValue().getParentValue() \
                                           == portal_simulation :