make sure that the context is not None

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3162 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/MatrixBox.py

@@ -360,6 +360,7 @@ class MatrixBoxValidator(Validator.Validator):
         context = here
         if getter_method_id not in (None,''):
           context = getattr(here,getter_method_id)()
+          if context is None: return {}
         cell_getter_method = context.getCell
 
         # This is required when we have no tabs