Merge branch 'lh/error_code' into 'master'

添加微信支付错误码



See merge request !8

Author: 杨国帅

src/WxPay.php

@@ -24,6 +24,9 @@ class WxPay extends \lspbupt\curl\CurlHttp
     const PAY_TRADE_TYPE_JSAPI = 'JSAPI';
     const PAY_TRADE_TYPE_NATIVE = 'NATIVE';
     const PAY_TRADE_TYPE_MWEB = 'MWEB';
+
+    const PAY_ERROR_CODE_PAID = 'ORDERPAID';
+    const PAY_ERROR_CODE_CLOSED = 'ORDERCLOSED';
     /**
      * @var string 商户号，见开户邮件
      */