Raise an explicit error if a model line has no resource

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@21015 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/PaySheetTransaction.py

@@ -348,6 +348,9 @@ class PaySheetTransaction(Invoice):
         continue
 
       service          = model_line.getResourceValue()
+      if service is None:
+        raise ValueError, 'Model Line %s has no resource' % (
+                                        model_line.getRelativeUrl())
       title            = model_line.getTitleOrId()
       int_index        = model_line.getFloatIndex()
       base_amount_list = model_line.getBaseAmountList()