php yar Yar_Client_Protocol_Exception

yar.php

class API {
    /**
     * the doc info will be generated automatically into service info page.
     * @params
     * @return
     */
    public function api($parameter='', $option = "foo") {
    return $parameter;
    }
 
  /**
  * generated
  * @return 
  */
    protected function client_can_not_see() {
    }
}


$service = new Yar_Server(new API());
$service->handle();


client.php

$client = new Yar_Client("");
$param = 'hello';
$ret = $client->api($param);
var_dump($ret);

如果在yar.php中出现报错，将会在client.php中报以下错误：
PHP Fatal error:  Uncaught exception 'Yar_Client_Protocol_Exception' with message 'malformed response header '