add: if ( groups.mode == 'error' ) { alert(groups.error); killACLManager(); return false; } 
context:   ajaxPost(stdAjaxPrefix+'&_mode=acljson', 'acl_params='+params, function() {      if(ajax.readyState == 4)      {        document.getElementById(aclManagerID+'_main').innerHTML = '';        document.getElementById(aclManagerID + '_back').style.display = 'none';        document.getElementById(aclManagerID + '_next').value = 'Next >';        groups = parseJSON(ajax.responseText);        aclDataCache = groups;        thispage = strToPageID(title);        groups.page_id = thispage[0];        groups.namespace = thispage[1];        __aclBuildSelector(groups);      }    });
meta: 3765	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/3765/1aea4491adc71b27748e575755ca6cf42a9981eb/acl.js/buggy/includes/clientside/static/acl.js