[Plugin: WordPress Wiki] Cannot modify header information

I get an error with the WordPress Wiki plugin after a fresh installation. When I save any page after activating the plugin, I get this:

Warning: Invalid argument supplied for foreach() in /data02/magnolia/public_html/wp-content/plugins/wordpress-wiki/wordpress-wiki.php on line 740

Warning: Cannot modify header information – headers already sent by (output started at /data02/magnolia/public_html/wp-content/plugins/wordpress-wiki/wordpress-wiki.php:740) in /data02/magnolia/public_html/wp-includes/pluggable.php on line 868