Cleanup throws error if TestCafe if Node.js instance was started with "--watch"

[Klaster1]

What is your Scenario?

I wrote some custom functions for TestCafe and decided to cover these with tests. The test setup consists of a Node.js built-in test runner that spawns TestCafe and asserts against TestCafe JSON reports. As goes with tests, you often want to run them in a watch mode.

What is the Current behavior?

What spawned from execSync, spawn or manually created runner instance (the createTestcafe API) and with the "--watch" flag, TestCafe runs the tests and throws.

TypeError: Cannot read properties of undefined (reading 'resolve')
    at CleanupProcess._onResponse (C:\dev\testcafe-repeat-test\node_modules\testcafe\lib\utils\temp-directory\cleanup-process\index.js:39:37)
    at ChildProcess.<anonymous> (C:\dev\testcafe-repeat-test\node_modules\testcafe\src\utils\temp-directory\cleanup-process\index.js:96:47)
    at ChildProcess.emit (node:events:519:28)
    at ChildProcess.emit (node:domain:488:12)
    at emit (node:internal/child_process:951:14)
    at processTicksAndRejections (node:internal/process/task_queues:83:21)

What is the Expected behavior?

TestCafe runs without throwing errors.

What is your TestCafe test code?

reproducer.zip

Steps to Reproduce

Create a TestCafe runner via the JS API and run an empty TestCafe test with it. When starting the .js, use "--watch" node argument.

TestCafe version

3.6.2

Node.js version

20.15.0

Platform(s) and version(s)

WIndows 11

[Klaster1]

Debugging indicates that this method does not validate the message contents. After I add if (!response.id) return to _onResponse, everything goes back to normal.

How a Node.js watch message payload looks:

{
  'watch:require': [
    'C:\\dev\\testcafe-repeat-test\\node_modules\\testcafe\\lib\\utils\\temp-directory\\cleanup-process\\commands.js'
  ]
}

[github-actions[bot]]

We appreciate you taking the time to share information about this issue. We reproduced the bug and added this ticket to our internal task queue. We'll update this thread once we have news.