public function isActionError($keys = null) {
        $errors = $this->getAttribute(ACTION_ERRORS_KEY);
        if (!$errors)
            return false;

        if (is_string($keys))
            $keys = [$keys];

        if (is_array($keys)) {
            foreach ($keys as $key) {
                if (key_exists($key, $errors)) return true;
            }
            if ($keys)
                return false;
            $keys = null;
        }

        if (is_null($keys))
            return true;
        throw new IllegalTypeException('Illegal type of parameter $keys: '.gettype($keys));
    }