Error handling in links_group_html

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/Naaya@19779 a0171fae-0946-0410-966d-b1775066cd26
Released 3.2.19, new version 3.2.20

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/Naaya@19782 a0171fae-0946-0410-966d-b1775066cd26