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function block_core_navigation_get_fallback_blocks() {
	$page_list_fallback = array(
		array(
			'blockName' => 'core/page-list',
		),
	);

	$registry = WP_Block_Type_Registry::get_instance();

	// If `core/page-list` is not registered then return empty blocks.
	$fallback_blocks = $registry->is_registered( 'core/page-list' ) ? $page_list_fallback : array();

	if ( class_exists( 'WP_Navigation_Fallback' ) ) {
		$navigation_post = WP_Navigation_Fallback::get_fallback();
	} else {
		$navigation_post = Gutenberg_Navigation_Fallback::get_fallback();
	}

	// Use the first non-empty Navigation as fallback if available.
	if ( $navigation_post ) {
		$parsed_blocks  = parse_blocks( $navigation_post->post_content );
		$maybe_fallback = block_core_navigation_filter_out_empty_blocks( $parsed_blocks );

		// Normalizing blocks may result in an empty array of blocks if they were all `null` blocks.
		// In this case default to the (Page List) fallback.
		$fallback_blocks = ! empty( $maybe_fallback ) ? $maybe_fallback : $fallback_blocks;
	}

	/**
	 * Filters the fallback experience for the Navigation block.
	 *
	 * Returning a falsey value will opt out of the fallback and cause the block not to render.
	 * To customise the blocks provided return an array of blocks - these should be valid
	 * children of the `core/navigation` block.
	 *
	 * @since 5.9.0
	 *
	 * @param array[] default fallback blocks provided by the default block mechanic.
	 */
	return apply_filters( 'block_core_navigation_render_fallback', $fallback_blocks );
}