微信小程序订阅消息后出错

1. 问题：用一按钮触发发送订阅小程序消息（内容写死）调用云函数后出现错误代码，但小程序端可以接收到消息

2.错误代码：_订阅失败 Error: errCode: -404011 cloud function execution error | errMsg: cloud.callFunction:fail requestID 063184d2-56ce-474d-83f2-2349b16d26f2, cloud function service error code -504002, error message TypeError: Do not know how to serialize a BigInt

3.我的代码如下：
调用云函数的JS：

tuisong() {
    console.log(this.data.rec)
    var item = {
      "time1": {
        "value": this.dateFormat(this.data.rec[1].cdate)
      },
      "thing2": {
        "value":  this.data.rec[1].line
      },
      "thing3": {
        "value": this.data.rec[1].postion
      },
      "thing4": {
        "value": this.data.rec[1].status
      }
    }
    wx.requestSubscribeMessage({
      tmplIds: ['R88OQ7kzfTRYe0yFXbdtz_gtPQtlPGc-bt9V-TzQAZE'], //这里填入我们生成的模板id
      success: res => {
        if (res.errMsg === 'requestSubscribeMessage:ok') {
          console.log('授权成功', res)
          wx.cloud.callFunction({
            name: 'getopenid',
          }).then(res=>{
            console.log('当前OPENID是',res.result.openid)
            this.setData({
              openid:res.result.openid
            })
            wx.cloud.callFunction({
              name: 'send',
              data: {
                data: item,
                openid: this.data.openid,
                templateId: 'R88OQ7kzfTRYe0yFXbdtz_gtPQtlPGc-bt9V-TzQAZE',
              }}).then(res=>{
                console.log('订阅成功', res)
              })
              .catch(res=>{
                  console.log('订阅失败', res)
              })
          })
        }
      },
      fail: res => {
        console.log('授权失败', res)
      }
    })
  },

getopenid云函数：

const cloud = require('wx-server-sdk')

cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV }) // 使用当前云环境

// 云函数入口函数
exports.main = async (event, context) => {
  const wxContext = cloud.getWXContext()

  return {
    event,
    openid: wxContext.OPENID,
    appid: wxContext.APPID,
    unionid: wxContext.UNIONID,
  }
}

send云函数：

```javascript
const cloud = require('wx-server-sdk')

cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
}) 

exports.main = async (event, context) => {
  return cloud.openapi.subscribeMessage.send({
    touser: event.openid,
    page: 'pages/query/index/index',
    data: event.data,
    templateId: event.templateId,
  })
};

云函数 的问题 TypeError:不知道如何序列化BigInt