Fix bug when no page was selected for a custom post type archive

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Types
 
+## 2.4.2 - 2019-10-17
+
+- Fixed bug when no page was selected for a custom post type archive in `Post_Type_Page_Option`.
+
 ## 2.4.1 - 2019-08-05
 
 - Added filter to update the title for the post type archive when using `post_type_archive_title()`.

lib/Post_Type_Page.php

@@ -53,6 +53,14 @@ public function __construct( $post_type, $post_id, $args = [] ) {
 	 * Inits hooks.
 	 */
 	public function init() {
+		/**
+		 * Bail out if no valid post ID is provided or post ID is 0, which happens when no page is
+		 * selected from dropdown-pages.
+		 */
+		if ( ! $this->post_id ) {
+			return;
+		}
+
 		add_filter( 'register_post_type_args', [ $this, 'update_archive_slug' ], 10, 2 );
 		add_filter( 'wp_nav_menu_objects', [ $this, 'filter_wp_nav_menu_objects' ], 1 );
 		add_filter( 'post_type_archive_title', [ $this, 'set_post_type_archive_title' ], 10, 2 );