Current code in node.module
<?php
function node_help($path, $arg) {
...
case 'node/%/edit':
$node = node_load($arg[1]);
$type = node_type_load($node->type);
return (!empty($type->help) ? '<p>'. filter_xss_admin($type->help) . '</p>': '');
?>Throws notice and because usage of arg()
Notice: Trying to get property of non-object in node_help() (line 135 of core/modules/node/node.module).