minification is messing up node-fetch's detection of abort signals

I’m using nodemailer-mailgun-transport. When attempting to call transporter.sendMail, I’m getting:

TypeError: Expected signal to be an instanceof AbortSignal

The stack trace is kinda useless because it’s minified. Also, because mailgun-js bundles all its deps with webpack, it’s pretty difficult to find, but I’m pretty sure here’s where the mailgun-js code gets involved: https://github.com/mailgun/mailgun-js/blob/28c71ded8b15dfa84d5933c9d458b834aa952d7a/lib/request.ts#L76

After investigating, I realized that node-fetch attempts to validate whether signal is an AbortSignal based on the name of the constructor.

In the latest stable version of node-fetch:

https://github.com/node-fetch/node-fetch/blob/v2.6.1/src/request.js#L42

And in the v3 beta it’s still based on the name, but is implemented slightly differently:

https://github.com/node-fetch/node-fetch/blob/v3.0.0-beta.9/src/utils/is.js

In any case, the minification of mailgun-js is causing this issue.

Suggested solution

At the very least, don’t minify. This would solve the problem. Also, you may have a reason to bundle, but that’s pretty unusual so I’m curious why you’re doing it. Can you avoid it? In my experience people handle bundling themselves for stuff like this.

[kentcdodds]

For anyone else who only really needs to send simple emails (like me), here’s what I wrote to do that with the API directly:

type MailgunMessage = {
  to: string
  from: string
  subject: string
  text: string
  html: string
}

const auth = `${Buffer.from(`api:${mailgunSendingKey}`).toString('base64')}`

function sendEmail(message: MailgunMessage) {
  return fetch(`https://api.mailgun.net/v3/${mailgunDomain}/messages`, {
    method: 'post',
    body: new URLSearchParams(message),
    headers: {
      Authorization: `Basic ${auth}`,
    },
  })
}

Docs:

• https://documentation.mailgun.com/en/latest/api-intro.html#authentication
• https://documentation.mailgun.com/en/latest/api-sending.html#sending

Look mah, no dependencies!

[kentcdodds]

Just realized why this was working a few weeks ago and suddenly stopped working. 8 days ago, nodemailer-mailgun-transport switched from the old mailgun-js to this mailgun.js: https://github.com/orliesaurus/nodemailer-mailgun-transport/commit/9c6596ac48f3371291a63e2cf700a87ba450067a

So yeah, anyway, I’m not sure why nobody else has reported this issue because from what I can tell, this shouldn’t work for anyone using mailgun.js on the server.