prevent errors when section is not defined

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@19797 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/BalanceTransaction.py

@@ -150,6 +150,8 @@ class BalanceTransaction(AccountingTransaction, Inventory):
     getInventoryList = self.getPortalObject()\
                             .portal_simulation.getInventoryList
     section_uid = self.getDestinationSectionUid()
+    precision = 2
+    if section_uid is not None:
       precision =  self.getDestinationSectionValue()\
                         .getPriceCurrencyValue().getQuantityPrecision()
     default_inventory_params = dict(