[Advanced Category Excluder]

Whenever I land on a missing page (ex. http://www.coreytegeler.com/bolivares/asda) I am given a bunch of Undefined variable errors pointing to line 446 in advanced-category-excluder.php

The bold line below is line 446

function ace_get_section()
{
	global $wp_query, $ace_targets;

	if (is_array($ace_targets))
	{
		foreach ($ace_targets as $key=>$val)
		{
		  if (!empty($wp_query->$key) && $wp_query->$key == 1) $filter = $key;
		}
	}

<strong>	return $filter;</strong>
}

Any idea what the root of this problem is and how to fix it?