public function addCustomErrors($errors)
    {
        if ($errors) {
            foreach ($errors as $error) {
                if (!is_a($error, 'AV\Form\FormError')) {
                    throw new InvalidArgumentException('Custom errors must be AV\Form\FormError objects');
                }
                else {
                    $this->errors[] = $error;
                }
            }
        }

        // Call isValid to update valid status in restore data handlers
        $this->isValid();
    }