facetwp add tags to category facet

custom-hooks.php

<?php

add_filter( 'facetwp_indexer_row_data', function( $rows, $params ) {
	if ( 'cases_topics' == $params['facet']['name'] ) {
		$post_id = $params['defaults']['post_id'];
		$tags = get_tags( $post_id );
		if ( !empty( $tags ) ) {
			foreach ( $tags as $tag ) {  
				$new_row = $params['defaults'];
				$new_row['facet_source'] = 'tax/post_tag';
				$new_row['facet_value'] = $tag->slug;
				$new_row['facet_display_value'] = $tag->name;
				$new_row['term_id'] = $tag->term_id;
				$rows[] = $new_row;
			}
		}
	}
	return $rows;
}, 10, 2 );