Ncc: 0.24.1 TypeScript compilation triggers Slack SDK error

[ataylorme]

I'm updating dependencies in my project (yay!) but I'm having some issues with the Slack Node SDK and @vercel/ncc.

I am maintaining a serverless function that reacts to interactive Slack messages. I am using the Slack SDK in a TypeScript environment and compiling my code with ncc for deployment to AWS Lambda.

Updating ncc from 0.23.0 to 0.24.1 throws a new error when running my compiled Lambda function.

The compiled code (with no changes to the source) from ncc version 0.24.1 triggers the error Error: Attempt to inherit from WebClient methods without inheriting from WebClient in the Slack SDK

Here is how I am using the Slack SDK (non-relevant code removed for brevity):

import {WebClient as SlackWebClient} from '@slack/web-api'
(async () => {
  // The slack token is fetched from SSM
  const {slackToken} = await getSecrets({environment})
  const slackClient = new SlackWebClient(slackToken)
  await slackClient.chat.postMessage({
    channel: channelID,
    thread_ts: messageID,
    text: `Some message text`,
  })
})

which aligns with their Posting a message with Web API documentation

I was able to compile my code with TypeScript directly, without ncc, and it does not have any issues. I would prefer to use ncc though to avoid uploading unnecessary dependencies when I deploy my serverless function. With nnc the function size is small. With all of node_modules sent to Lambda it is 60M.

P.S. thank you for creating ncc, it is fantastic ❤️

[ataylorme]

I setup a new repo https://github.com/ataylorme/ncc-0.24.1-slack-compilation-issue that re-creates the issue.

The code compiled with NCC 0.23.0 passes the mocked tests I setup but the same code compiled with NCC 0.24.1 throws the Error: Attempt to inherit from WebClient methods without inheriting from WebClient error.

You can see the test results at https://github.com/ataylorme/ncc-0.24.1-slack-compilation-issue/runs/1131194239

You can also clone the repo locally, update the NCC version, and run the tests with npm test.

Hopefully this helps you in diagnosing the issue.

[ataylorme]

I was also able to fork NCC and add a unit test for the Slack NodeJS SDK which failed in GitHub Actions with the same Error: Attempt to inherit from WebClient methods without inheriting from WebClient

[ataylorme]

Also, if it helps, the error being thrown from the Slack Node SDK is here: https://github.com/slackapi/node-slack-sdk/blob/main/packages/web-api/src/methods.ts#L37

[dperrett]

I'm having the same issue with @slack/web-api ^5.12.0 plus NCC 0.24.1:

Error: Attempt to inherit from WebClient methods without inheriting from WebClient

If I roll back to NCC 0.23.0 everything works.

[ataylorme]

This has been fixed in ncc version 0.25.0. A big thank you to the Vercel team for maintaining ncc!