improved problem message

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@11599 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5OOo/Document/OOoDocument.py

@@ -148,7 +148,7 @@ class OOoDocument(DMSFile, CachingMixin):
     try:
       self._convert()
     except xmlrpclib.Fault,e:
-      return self.returnMessage('Problem: %s' % str(e),2)
+      return self.returnMessage('Problem: %s' % (str(e) or 'undefined'),2)
     return self.returnMessage('converted')
 
   security.declareProtected(Permissions.AccessContentsInformation,'getTargetFormatList')