erp5_xhtml_style: fix generation context_box while ui_actions empty

product/ERP5/bootstrap/erp5_xhtml_style/SkinTemplateItem/portal_skins/erp5_xhtml_style/context_box_render.zpt

@@ -308,6 +308,7 @@
             </li>
             <li class="btn-group pull-right" tal:condition="list_mode">
               <a class="configure btn btn-default" title="Configure"
+                 tal:condition="ui_actions"
                  tal:attributes="href python: portal.ERP5Site_renderCustomLink(ui_actions[0]['url'], http_parameter_list, dialog_category='object_ui')"
                  i18n:attributes="title" i18n:domain="ui">
                 <i class="fa fa-wrench fa-lg"></i>