Duplex/Transform stream writableObjectMode ignored

[ccarcaci]

Version

14.17.5

Platform

Linux *** 5.11.0-25-generic #27~20.04.1-Ubuntu SMP Tue Jul 13 17:41:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

No response

What steps will reproduce the bug?

Create an usual Transform stream with writableObjectMode: true.

i.e.

type Packet = { ... }

const packetParser = (): stream.Transform => {
  const transformStream = new stream.Transform({
    writableObjectMode: true,
    transform(packet: Buffer, _, callback) {
      const parsedPacketObject: Packet = parser.parse(packet)
      this.push(parsedPacketObject)
      callback()
    },
  })

  return transformStream
}

Following the cascade calls of this.push() I went into:
https://github.com/nodejs/node/blob/v14.17.5/lib/internal/streams/readable.js#L203
this line calls the readableAddChunk() function which is not taking into account the writableObjectMode flag in line: https://github.com/nodejs/node/blob/v14.17.5/lib/internal/streams/readable.js#L217

This results into the exception:
Exception has occurred: TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be of type string or an instance of Buffer or Uint8Array. Received an instance of Packet

How often does it reproduce? Is there a required condition?

No, it is reproducing all the times.

What is the expected behavior?

The when I call push I expect to call the writable part of Transform/Duplex stream which takes into account the writableObjectMode flag.

What do you see instead?

I see that the push call goes through the readable part of Transform/Duplex stream.

Additional information

No response

[ccarcaci]

N/A.
I've misunderstood the API doc.