我在ibm-app-conect中开发，遇到了一个问题。
我使用后端soap服务并将其转换为JSON。
当我测试我的服务（OK）时，我没有问题，但是当我用错误案例测试我的服务时，我得到一个通用的错误消息。

在该图像中，我收到了通用错误消息。

如何控制此错误，以便得到图像中显示的以下消息？

下面是我在这个gatewayscript或程序中使用的代码。

var apim=require('apim');

  // IMPORT
  const transform = require('transform');
  const converter = require('json-xml-converter');

  // CONSTANTES
  const HTTP_CODE_FUNCTIONAL = 209;
  const HTTP_CODE_OK = 200;
  const HTTP_CODE_500 = 500;
  const HTTP_MESSAGE_500 = 'Internal Server Error';
  const codeErrors = [500, 403, 503, 404];

  // VARIABLES
  let bodyProvider =  apim.getvariable('message.body');
  let httpCode = apim.getvariable('message.status.code');
  let backSideTransport = apim.getvariable('message.headers.X-Backside-Transport');

  console.log("probando:" + backSideTransport);

  // SERVICE VARIABLES
  let tagBackend = '//xmlns:GetClienteObservadosOFACR1SelResponse';
  let tagNamespace = 'http://tempuri.org/';
  let dataType = 'xml';
  let nsVar = 'xmlns';

  // INIT VALIDATE PROCCESS
  manageResponse(httpCode,bodyProvider,dataType,tagBackend,nsVar,tagNamespace);

/*---------------------------- Operation section ----------------------------*/

// Especific function: Validate items ok
function validateEspecific(sJson) {

  let okSrvCods = ['OK'];
  let flagMapInGateway = true;
  let texto = '';   
  
  if (typeof sJson.GetClienteObservadosOFACR1SelResponse.GetClienteObservadosOFACR1SelResult.NewDataSet.Datos == undefined
   || sJson.GetClienteObservadosOFACR1SelResponse.GetClienteObservadosOFACR1SelResult.NewDataSet.Datos == null
   || sJson.GetClienteObservadosOFACR1SelResponse.GetClienteObservadosOFACR1SelResult.NewDataSet.Datos == '') {
        texto += '{ "blackListFlag": "false"}';
    }else{
        texto += '{ "blackListFlag": "true"}';
    }
    generateResponseMessage(200,'OK','0','EJECUCION CON EXITO','0000', 'OK',texto);
  
}

// Especific function: Create response 200
function mapJsonOK(codError, msgError, respuesta) {
    let rsMessage = '{  "sequenceId":  "' + respuesta.trim() + '"}';
    generateResponseMessage(200,'OK','0','EJECUCION CON EXITO',codError, msgError,rsMessage);
}

/*---------------------------- Operation section ----------------------------*/

/*------------------------------ Free section -------------------------------*/
function defaultVal(field, def) {
    field = typeof field !== 'undefined' && field != null && field != '' ? field : def;
    return field;
}
/*------------------------------ Free section -------------------------------*/

/*-------------------------- Framework IFX section --------------------------*/

//Generic function: Manage response
function manageResponse(httpCode,bodyProvider,dataType,tagBackend,nsVar,tagNamespace){
    
  if (codeErrors.includes(httpCode)){
      // Separar segun codigo
      generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');
  }else if(200 == httpCode){

      if(bodyProvider){
                    validateAndTransformBody(dataType, bodyProvider, tagBackend, nsVar, tagNamespace);
      }else{
          generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');
      }
  }else{
      // Codigo HTTP no conocido, genera respuesta generica
      generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');
  }
  
}

// Generic function: Validate dataType and transform body
function validateAndTransformBody(dataType,bodyProvider, tagBackend, nsVar, tagNamespace) {

    if(dataType == 'xml' ){
  
    let options = { 'expression': '//tns1:GetClienteObservadosOFACR1SelResponse', 'xmldom': bodyProvider, 'namespace': { 'tns1' : 'http://tempuri.org/'}};  
    let option = { omitXmlDeclaration: true };

    transform.xpath(options, function(err, xmlNodeList) {
        if (err) { session.output.write(err);
      }else{

        let output = XML.stringify(option, xmlNodeList);
        let xml = XML.parse(output);
        let sJson = converter.toJSON('badgerfish',xml);
        validateEspecific(sJson);

      }
    });
  
  }else{ validateEspecific(bodyProvider); }
  
}

// Generic function: Propagate to Map Policy
function skipToMap(flag) {
    apim.setvariable('message.headers.skip', true);
}

// Generic function: Responde cabecera de error IFX
function generateResponseMessage(codeHttp,reasonHttp,busResponseCode,busResponseMessage,srvResponseCode,srvResponseMessage,responseMessage){
    
    let globalTransaccionId = apim.getvariable('message.headers.X-Global-Transaction-ID');
    
    apim.setvariable('message.headers','','clear');
    apim.setvariable('message.body','','clear');
    
    apim.setvariable('message.headers.busResponseCode', busResponseCode);
    apim.setvariable('message.headers.busResponseMessage', busResponseMessage);
    apim.setvariable('message.headers.srvResponseCode', srvResponseCode);
    apim.setvariable('message.headers.srvResponseMessage', srvResponseMessage);
    apim.setvariable('message.headers.X-Global-Transaction-ID', globalTransaccionId);
    
    if(responseMessage != null){
        apim.setvariable('message.body', responseMessage);
    }
    
    apim.setvariable('message.status.code', codeHttp);
    apim.setvariable('message.status.reason', reasonHttp);
    apim.output('application/json');
    
}

/*-------------------------- Framework IFX section --------------------------*/

function pad(n, width, z) { z = z || '0'; n = n + ''; return n.length >= width ? n : new Array(width - n.length + 1).join(z) + n; }

我尝试使用头X-Backside-Transport，但我无法修复它。

if (codeErrors.includes(httpCode)){

let backSideTransport = apim.getvariable('message.headers.X-Backside-Transport');
      // Separar segun codigo
      generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');

  }else if(200 == httpCode && backSideTransport == 'FAIL FAIL'){

          generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '502','An error occurred trying to  invoke external services.');
     apim.setvariable('message.headers.srvResponseCode', HTTP_CODE_500);
     apim.setvariable('message.headers.srvResponseMessage', HTTP_MESSAGE_HTTP_500);
      }else{
          generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');
      }
  }else{
      // Codigo HTTP no conocido, genera respuesta generica
      generateResponseMessage(HTTP_CODE_500, HTTP_MESSAGE_500, '302','An error occurred trying to invoke external services.');
  }
}