child_process: document the error when cwd does not exist

[FeelyChau]

If the option cwd does not exist, the error ENOENT is the same as the error emitted when the command does not exist, it's confusing.

Checklist

• documentation is changed or added
• commit message follows commit guidelines

[Trott]

Welcome @FeelyChau and thanks for the pull request. ENOENT means a path (whether file, directory, or other) does not exist. The additional information included with the error should make it clear whether the issue is the directory path or the command path. I'm not really sure this is a good thing to add to the docs. The errors should be self-explanatory. But let's see if others think differently. @nodejs/documentation @nodejs/child_process

[FeelyChau]

@Trott Thanks for review.
Here is the code:

const ChildProcess = require('child_process');

const cp = ChildProcess.spawn('/usr/local/bin/node', [], { cwd: 'path_not_exists' });

cp.on('error', (err) => {
    console.log(err);
})

the output:

Error: spawn /usr/local/bin/node ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:267:19)
    at onErrorNT (internal/child_process.js:469:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21) {
  errno: 'ENOENT',
  code: 'ENOENT',
  syscall: 'spawn /usr/local/bin/node',
  path: '/usr/local/bin/node',
  spawnargs: []
}

The error is not specific.
I think the reason is libuv throw the ENOENT only, so we could not know the specific reasons.
Look at:

node/deps/uv/src/unix/process.c

Line 342 in 3751662

uv__write_int(error_fd, UV__ERR(errno));

[yorkie]

I did address a bug related in mine until I found the call to chdir() at libuv. So IMO the other developers may not have an idea about considering it's an error caused by the cwd path. The cwd in options usually means it's an optional argument, and it wouldn't throw the same error from the required arguments which may be a little bit confusing :)

[aduh95]

I'm good with this personally.

[github-actions]

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[aduh95]

Landed in bea9857