调用阿里云物联网平台的nodejs-SDK（@alicloud/pop-core），请求queryDevice，出现Promise { <pending> }这样的结果，是什么原因

出错代码如下：

var RPCClient = require('@alicloud/pop-core').RPCClient;

var client = new RPCClient({
  accessKeyId: '<accessKeyId>',
  accessKeySecret: '<accessKeySecret>',
  endpoint: 'http://iot.cn-shanghai.aliyuncs.com',
  apiVersion: '2017-04-20'
});

var params = {
    DeviceName: "<DeviceName>",
      AccessKeyId: "<AccessKeyId>",
      ProductKey: "<ProductKey>",
      DeviceSecret: '<DeviceSecret>',
      PageSize: 10,
      CurrentPage: 1
}

var options = {
    Format: "JSON",
    SignatureMethod: "HMAC-SHA1",
    SignatureVersion: "1.0",
    RegionId: "cn-shanghai",
    timeout: 3000, 
      formatAction: true, 
      formatParams: true, 
      method: 'GET', 
      headers: {}
}

try{
    var result = client.request('queryDevice', params, options);
    console.log(result);
}catch(err){
    console.log(err);
}