After I used CPT-onomies to create this custom post type, the following error appears at the top of every page both on the displayed site and in the admin interface:
Notice: Undefined offset: 1 in /[...]/wp-includes/post.php on line 1155
which points to:
1154 // Singular base for meta capabilities, plural base for primitive capabilities. 1155 list( $singular_base, $plural_base ) = $args->capability_type;
This error message goes away if I deactivate CPT-onomies. (I deactivated all other installed plugins, so the problem appears to be solely between CPT-onomies and WordPress 3.4.2.)
Please let me know if you see something to tweak either in your plugin or in my CPT definition to work around this problem.