lumen-framework: Can't call parameter on routeResolver array

Trying to read route parameters from my Middleware class with $request->route(‘id’). This gives me the error that it can’t call parameter() on an array. When I look at the source code, the $this->getRouteResolver() returns an array. Is this a bug?

public function route($param = null)
{
  $route = call_user_func($this->getRouteResolver());

  if (is_null($route) || is_null($param)) {
    return $route;
  } else {
    return $route->parameter($param);
  }
}