navigation-link pre wp 6.5 variations

navigation-link.php

<?php 

function register_block_core_navigation_link() {
	$variations = array();
	if ( ! method_exists( 'WP_Block_Type', 'get_variations' ) ) {
		$variations = build_navigation_link_block_variations();
	}
	register_block_type_from_metadata(
		__DIR__ . '/navigation-link',
		array(
			'render_callback' => 'render_block_core_navigation_link',
			'variations'      => $variations,
		)
	);
}