get_post_type_capabilities() assumes $args->capabilities is an array

[wpsmith]

get_post_type_capabilities() assumes $args->capabilities is an array and should check and confirm it. Otherwise a warning appears: Warning: array_merge() [function.array-merge]: Argument # 2 is not an array in /home/username/public_html/wp-includes/post.php on line 1183. I discovered this when I accidentally set this to null instead of array().

Type setting it seems to clear the warning, if we want to clear the warning.

$capabilities = array_merge( $default_capabilities, (array)$args->capabilities );

This feels like a user error, and a error that should be left in place so that Developers *know* they've passed something wrong in..