Warning: in_array()

when clicking a new wiki link on my website it opens a new wiki page inner my wp site.
i get this bug in the navigation area:

Warning: in_array() [function.in-array]: Wrong datatype for second argument in /.../www.xxxxxxxx.com/wp-includes/nav-menu-template.php on line 564

i think its because of the plugin – anybody has some experience on this bug??

https://www.ads-software.com/plugins/wiki-embed/