Here's an important one to put in your pages. It will block any errors in script syntax that may be laying dormant in your pages. Just a precaution...
<script language="JavaScript">
// Source: CodeFoot.com
function blockError(){return true;}
window.onerror = blockError;
</script>
<script language="JavaScript">
// Source: CodeFoot.com
function blockError(){return true;}
window.onerror = blockError;
</script>