PayPal-PHP-SDK 代码错误

我正在使用PayPal-PHP。SDK，我想得到代码错误。当我输入错误的信用卡数据时，我得到这个 JSON 作为答案：

{
"name":"CREDIT_CARD_REFUSED",
"message":"Credit card was refused",
    "information_link":"https://developer.paypal.com/webapps/developer/docs/api    /#CREDIT_CARD_REFUSED",
"debug_id":"63a9cf220d272"
}

或者这个：

{"name":"VALIDATION_ERROR",
       "details":[
            {"field":"payer.funding_instruments[0].credit_card.expire_month","issue":"Must not be blank"},
            {"field":"payer.funding_instruments[0].credit_card.expire_year","issue":"Must not be blank"},
            {"field":"payer.funding_instruments[0].credit_card.cvv2","issue":"Must be numeric"}],
       "message":"Invalid request - see details","information_link":"https://developer.paypal.com/webapps/developer/docs/api/#VALIDATION_ERROR","debug_id":"8e61a15a1bf4a"}

但是我需要错误代码。我怎样才能得到它？

谢谢