check if a quantity is None

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@4074 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/SimulationMovement.py

@@ -477,6 +477,8 @@ class SimulationMovement(Movement):
       return 1
 
     d_quantity = delivery.getQuantity()
+    if d_quantity is None:
+      d_quantity = 0
     quantity = self.getCorrectedQuantity()
     d_error = self.getDeliveryError()
     if quantity is None: