protected function callableOrFail(string $operator): callable
    {
        $callable = $this->config($operator, 'callable');

        if (is_string($callable) && method_exists($this->model, $callable)) {
            return [$this->model, $callable];
        }

        if (is_callable($callable)) {
            return $callable;
        }

        throw new DynamicMutatorNotCallableException('The given callable is invalid!', 0, null, [
            'callable' => $callable,
            'handler'  => $this->getName(),
        ]);
    }