Getting foreach error on empty posts..

custom columns

function columns( $columns, $post_type = 'post' ) {
			$post_type = get_post_type();
			
			if ( !post_type_supports( $post_type, 'thumbnail' ) )
				return;
				
			if ( !$columns )
				return;
				
			if ( !WP_List_Table::has_items() )
				return;
				
			$new = array();
			
			foreach( $columns as $key => $title ) {
				if ( $key == 'title' ) // Put the Thumbnail column before the Title column
					$new['featured-image'] = __( 'Image', self::domain );
				$new[$key] = $title;
			}
			return $new;
		}


    WARNING: C:\xampp\htdocs\demo\wp-admin\includes\class-wp-list-table.php:661 - Invalid argument supplied for foreach()
    WARNING: C:\xampp\htdocs\demo\wp-admin\includes\class-wp-list-table.php:631 - array_keys() expects parameter 1 to be array, null given
    WARNING: C:\xampp\htdocs\demo\wp-admin\includes\class-wp-list-table.php:631 - array_intersect() [function.array-intersect]: Argument #1 is not an array