protected function addError($error){

        $this->valid = false;

        if($error instanceof Exception){
            $this->errors[] = array(
                'file' => $error->getFile(),
                'line' => $error->getLine(),
                'message' => "[".get_class($error)."] ".$error->getMessage()
            );
        }elseif($error instanceof LibXMLError){
            $this->errors[] = array(
                'file' => $error->file,
                'line' => $error->line,
                'message' => "[".get_class($error)."] ".$error->message
            );
        }elseif(is_string($error)){
            $this->errors[] = array(
                'message' => $error
            );
        }
    }