llback menu or a WP_Error object.
	 */
	private static function create_default_fallback() {

		$default_blocks = static::get_default_fallback_blocks();

		// Create a new navigation menu from the fallback blocks.
		$default_fallback = wp_insert_post(
			array(
				'post_content' => $default_blocks,
				'post_title'   => _x( 'Navigation', 'Title of a Navigation menu' ),
				'post_name'    => 'navigation',
				'post_status'  => 'publish',
				'post_type'    => 'wp_navigation',
			),
			true // So that we can check whether the result is an error.
		);

		return $default_fallback;
	}

	/**
	 * Gets the rendered markup for the default fallback blocks.
	 *
	 * @since 6.3.0
	 *
	 * @return string default blocks markup to use a the fallback.
	 */
	private static function get_default_fallback_blocks() {
		$registry = WP_Block_Type_Registry::get_instance();

		// If `core/page-list` is not registered then use empty blocks.
		return $registry->is_registered( 'core/page-list' ) ? '<!-- wp:page-list /-->' : '';
	}
}