WordPress: Disable WP REST API JSON endpoints if user not logged in

disable-rest-endpoints.php

<?php
/*
 * Disable WP REST API JSON endpoints if user not logged in
 */
function chuck_disable_rest_endpoints( $access ) {
	if( ! is_user_logged_in() ) {
		return new WP_Error( 'rest_cannot_access', __( 'Only authenticated users can access the REST API.', 'disable-json-api' ), array( 'status' => rest_authorization_required_code() ) );
	}
  return $access;
}
add_filter( 'rest_authentication_errors', 'chuck_disable_rest_endpoints' );