do not assume that there is always a description

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@21120 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/DocumentationHelper/DCWorkflowDocumentationHelper.py

@@ -254,7 +254,7 @@ class DCWorkflowDocumentationHelper(DocumentationHelper):
     """
     variable_list = []
     for variable in  self.getInstance().variables.objectValues():
-      variable_list.append((variable.getId(), variable.title, variable.__dict__["description"]))
+      variable_list.append((variable.getId(), variable.title, variable.__dict__.get("description",'')))
     return variable_list
 
   security.declareProtected( Permissions.AccessContentsInformation, 'getVariableURIList' )