portal_preferences.getPreferredAccountingTransactionGap() can return None

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34501 20353a03-c40f-0410-a6d1-a30d3c3de9de

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountModule_getAccountListForTrialBalance.xml

@@ -658,7 +658,7 @@ if not per_account_class_summary:\n
   return line_list\n
 \n
 current_gap = selected_gap or \\\n
-                 portal.portal_preferences.getPreferredAccountingTransactionGap()\n
+                 portal.portal_preferences.getPreferredAccountingTransactionGap() or \'\'\n
 if current_gap.startswith(\'gap/\'):\n
   current_gap = current_gap[4:]\n
 def getAccountClass(account_relative_url):\n

bt5/erp5_accounting/bt/revision

-1167
\ No newline at end of file
+1168
\ No newline at end of file