child_process: ERR_INVALID_ARG_TYPE on .kill()

• Version: Electron v4.2.12 - Node v10.11.0
• Platform: Windows 10 64-bit
• Subsystem: child_process

We are getting the following stack trace when killing a child_process:

root ERROR TypeError [ERR_INVALID_ARG_TYPE]: The "err" argument must be of type number. Received type undefined
    at validateNumber (internal/validators.js:130:11)
    at Object.getSystemErrorName (util.js:1435:3)
    at errnoException (internal/errors.js:303:21)
    at ChildProcess.kill (internal/child_process.js:430:26)

From what I can make of it, it seems to be caused by the following code:

https://github.com/nodejs/node/blob/v10.x/lib/internal/child_process.js#L425-L439

    var err = this._handle.kill(signal);
    if (err === 0) {
      /* Success. */
      this.killed = true;
      return true;
    }
    if (err === UV_ESRCH) {
      /* Already dead. */
    } else if (err === UV_EINVAL || err === UV_ENOSYS) {
      /* The underlying platform doesn't support this signal. */
      throw errnoException(err, 'kill');
    } else {
      /* Other error, almost certainly EPERM. */
      this.emit('error', errnoException(err, 'kill'));
    }

Somehow, err seems to be undefined, making us land in the last else branch, but then errnoException doesn't know what to make out of it and throws the error that we see.

The issue only happens in Electron, so it might not be entirely related to Node, but I was wondering if this err value is expected to be undefined in some circumstance?

从 lib/internal/child_process.js 中被引用的范围开始，跟踪 err 值从 this._handle.kill(signal) 经过 internal/errors.js、util.js 和 internal/validators.js 的流程。在报告的 Electron 和 Node 版本下于 Windows 上复现 .kill() 失败，然后确定会产生 undefined 的平台条件，并记录或测试预期行为。