Handle another exception

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@23396 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/Document.py

@@ -1283,7 +1283,7 @@ class Document(PermanentURLMixIn, XMLObject, UrlMixIn, ConversionCacheMixin, Sna
       try:
         stripped_html = unicode(str(stripped_html), 
                                 charset_list[0]).encode('utf-8')
-      except UnicodeDecodeError:
+      except (UnicodeDecodeError, LookupError):
         return str(stripped_html)
     return stripped_html