Enable Event Tags and Categories on Gutenberg

<?php

/*
 * Note: this snippet is not fully tested
 *
 */

add_filter ('em_ct_categories', 'zzp_em_ct_categories' );
add_filter ('em_ct_tags', 'zzp_em_ct_categories' );
function zzp_em_ct_categories( $params ) {
 if ( defined( 'EM_GUTENBERG' ) AND EM_GUTENBERG ) {
  $params['show_in_rest'] = true;
 }
 return $params;
}