T5 Debug Hook

debug-hook.php

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: T5 Debug Hook
 * Description: Adds a list of registered filters and action for a hook. Call a page with <code>?hook=NAME</code> to see it.
 */

add_action( 'shutdown', 't5_debug_hook' );

function t5_debug_hook()
{
	if ( ! isset ( $_GET['hook'] ) or ! current_user_can( 'update_core') )
	{
		return;
	}

	$f = $GLOBALS['wp_filter'];

	if ( ! isset ( $f[ $_GET['hook'] ] ) )
	{
		print 'Nothing found for ' . esc_html( $_GET['hook'] );
		return;
	}

	print '<pre>' . esc_html( var_export( $f[ $_GET['hook'] ], TRUE ) ) . '</pre>';
}

Howdy, I'm getting a Fatal error: Nesting level too deep - recursive dependency?