How to avoid foreach error WebDevStudio’s WDS_Taxonomy_Radio taxonomy metabox class?

Question

Upon initialization of the class, you need to pass two parameters:

    public function __construct( $tax_slug, $post_types = array() ) {

So what you need to do is initialize like this:

 $custom_tax_mb = new WDS_Taxonomy_Radio( 'custom-tax-slug', array( 'post_type' ) );

In the second array you need to put the name of the post types for which you want to display the meta box in the admin. This is why the foreach() fails.