我尝试将表单数据写入一个json数据库文件，同时也使用nodeMailer在writeFile之前或之后执行，问题是，在我的代码中，只有writeFile看起来在执行，而nodeMailer没有执行，但是，如果我省略文件Write，nodeMailer就会执行，我就可以发送电子邮件。有谁能就如何运行这两个任务提供建议吗？

const messageDB = {
    messages: require('../models/messageDB.json'),
    setMessage: function (data) {
        this.messages = data
    }
}

const { body, validationResult } = require('express-validator')
const fs = require('fs')
const path = require('path')
const nodemailer = require('nodemailer')

exports.message_controller_get = (req, res, next) => {
    res.render('index')
}

exports.message_controller_post = [
  body('name', 'Full names must be specified').isLength({ min: 2, max: 40 }).trim(),
  body('email', 'Email address must be specified').isEmail().isLength({ min: 3, max: 40 }),
  body('msg', 'Message must be specified').isLength({ min: 20, max: 1000 }),

  (req, res, next) => {

    const errors = validationResult(req)

    if (!errors.isEmpty()) {
        
        console.log('there are errors: ' +  errors.array())
        return
    }
    const message = {
        name: req.body.name,
        email: req.body.email,
        msg: req.body.msg
    }
    const transporter = nodemailer.createTransport({
        host: 'smtp.ethereal.email',
        port: 587,
        auth: {
            user: 'lila.greenfelder71@ethereal.email',
            pass: 'DQnhbPkHBRzPU1UkAt'
        }
    });

    const mailOption = {
        from: 'Fred Foo 👻" <fred@homexclusiv.com>',
        to: 'payiyke@gmail.com',
        subject: `Message from ${req.body.email}:`,
        text: req.body.msg
    }
    
  
    messageDB.setMessage([...messageDB.messages, message])
    fs.writeFile(
        path.join(__dirname, '..', 'models', 'messageDB.json'),
        JSON.stringify(messageDB.messages),
        (err) => {
            if (err){
                return res.send(err)
            } else {
                transporter.sendMail(mailOption, (error, info) => {
                    if (error) {
                        console.log(error);
                        res.send('error')
                    } else {
                        console.log('Email sent :' + info.response)
                        res.send('success')
                    }
                })
               /*  return res.send('success') */
            }
            
        }
    )

    /* console.log(`${message.name}\t${message.email}`) */

    
    
  }
  
]

不用担心，密码是临时的