getTotalPrice should not raise an exception, even if getQuantity or getPrice returns None.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3179 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/SupplyLine.py

@@ -142,7 +142,9 @@ class SupplyLine(DeliveryLine, Path):
       """
         Returns the totals price for this line
       """
-      return self.getQuantity() * self.getPrice()
+      quantity = self.getQuantity() or 0.0
+      price = self.getPrice() or 0.0
+      return quantity * price
 
     def _getPrice(self, context):
        return 0.0