I get a rest_no_route error if I try to use a custom endpoint I’ve created. Is there any solution? I’m creating my theme routes inside a plugin class, but I don’t think this is a problem.
I’m using axios to get the data on front-end.

class theme_Rest_Routes extends WP_REST_Controller{

  public static function init()
  {
    add_action( 'rest_api_init', array( __CLASS__, 'register_routes') );
  }

  public function register_routes()
  {
    register_rest_route( 'theme/v1', '/menu/', array(
      'methods' => 'GET',
      'callback' => array(__CLASS__, 'theme_rest_menu'))
    );

  }

  public function theme_rest_menu( $request )
  {
    return wp_get_nav_menu_items('menu');
  }

}
theme_Rest_Routes::init();