TypeError: Response body object should not be disturbed or locked

[mattes3]

I get the TypeError message in this line here: https://github.com/fedify-dev/express/blob/0cba7a08a406bc3263b4055f0fc534b554af1459/src/index.ts#L82

I am running Express inside an AWS Lambda, using @codegenie/serverless-express as a wrapper.

When someone posts something to the Fedify inbox, the Lambda crashes with this error message. This does not happen on my dev computer, only when I run Fedify inside the Lambda function:

TypeError: Response body object should not be disturbed or locked
    at extractBody (node:internal/deps/undici/undici:5325:17)
    at new Request (node:internal/deps/undici/undici:9499:48)
    at fromERequest (file:///opt/nodejs/node_modules/@fedify/express/dist/index.js:52:10)
    at file:///opt/nodejs/node_modules/@fedify/express/dist/index.js:5:21
    at Layer.handle [as handle_request] (/opt/nodejs/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/opt/nodejs/node_modules/express/lib/router/index.js:328:13)
    at /opt/nodejs/node_modules/express/lib/router/index.js:286:9
    at Function.process_params (/opt/nodejs/node_modules/express/lib/router/index.js:346:12)
    at next (/opt/nodejs/node_modules/express/lib/router/index.js:280:10)
    at Function.handle (/opt/nodejs/node_modules/express/lib/router/index.js:175:3)

[ThisIsMissEm]

It's probably the Readable.toWeb() which I don't think forks the stream. Though worth double checking: what node.js version are you using on lambda?

[ThisIsMissEm]

A cursory look suggests that that package may be doing something funky with the request: https://github.com/CodeGenieApp/serverless-express/blob/mainline/src/request.js

[malkoG]

I added support for NestJS(@fedify/nestjs) based on @fedify/express, and I got same problem. I think, It is similar to this issue and it was solved by this PR. In this case, it was caused from Firebase Function

For @fedify/nestjs, Just replacing Readable.toWeb(req) to req.body worked. But, I am analyzing why this works and I don't know it could be applied to @fedify/express, too

[ThisIsMissEm]

I think you might be on the money there with that PR you linked @malkoG, however, it depends if the serverless-express package provides you such.

[ThisIsMissEm]

Looking deeper into that package, it looks like the body comes from the event, so is probably a string here: https://github.com/CodeGenieApp/serverless-express/blob/mainline/src/event-sources/aws/api-gateway-v2.js#L42

So you could do something like:

typeof req.body === 'string' ? req.body : Readable.toWeb(req)

or potentially:

function getBody(req) {
  if (typeof req.body === 'string') {
    return new ReadableStream({
      start(controller) {
        controller.enqueue(req.body)
        controller.close()
      },
    })
  } else {
    return Readable.toWeb(req)
  }
}