fix:bug

Helper/InvokeHelper.cs

@@ -236,7 +236,9 @@ namespace PTMedicalInsurance.Helper
                                 string output = JsonHelper.getDestValue(joRtn, "output");
                                 output = yhEncrypt.Decrypt(output);
                                 Global.writeLog("output明文：" + output);
-                                joRtn["output"] = JObject.Parse(output);
+                                if (!string.IsNullOrEmpty(output) && !output.Equals("null")) { 
+                                    joRtn["output"] = JObject.Parse(output);
+                                }
                                 Global.writeLog("解析后返参" + joRtn.ToString());
                             }
                         }