我正在尝试从Firebase云功能使用Mailgun的api发送电子邮件。我曾尝试在Cloud
Function中实现相同的nodejs教程，但是我总是收到“错误：无法处理请求”。请我做错了什么。

下面的云功能代码：

 <pre>
  <code>
 var functions = require('firebase-functions');

 var nodemailer = require('nodemailer');

  var auth = {
  auth: {
      api_key: '###################',
       domain: 's###############g'
   }
 }
 exports.helloWorld = functions.https.onRequest((request, response) => {
  response.send("Hello from Firebase!");
  });

   var nodemailerMailgun = nodemailer.createTransport(auth);

 exports.sendEmail = functions.https.onRequest((request, response) =>{
  //app.get('/', function(req, res) {
   test();
 });

  function test(){
     const mailOptions = {
        //Specify email data
            from: "info@xyz.com",
            //The email to contact
        to: "xyz@yahoo.com",
        //Subject and text data  
        subject: 'Hello from Mailgun',
        text: 'Hello, This is not a plain-text email, I wanted to test        some spicy Mailgun sauce in NodeJS! <a href="http://0.0.0.0:3030/validate?' +     req.params.mail + '">Click here to add your email address to a mailing     list</a>'
   };
    return smtpTransport.sendMail(mailOptions).then(() => {
    console.log("It works");
  });
}
</pre>

谢谢你的协助。