Context: sibling to #65506 (which moved the spawn timeout cleanup from 'exit' to 'close' so it also fires on spawn-time failures). This applies the same rule to the AbortSignal cleanup a few lines below in the same spawn() function

Description

A failed spawn emits 'error' and 'close' but never 'exit'. The timeout cleanup got fixed by #65506 for exactly this, but the AbortSignal dispose still sits only on 'exit', so after a failed spawn the abort listener stays attached to the user's signal

// lib/child_process.js, spawn()
const disposable = addAbortListener(signal, onAbortListener);
child.once('exit', disposable[SymbolDispose]); // never fires when the spawn itself failed

probed on a pristine main build (67a4416): after the 'error' of a failed spawn, the signal still carries the abort listener, and 'exit' never fires while 'close' does

this keeps the dispose on 'exit' (so the timing the existing test in test-child-process-spawn-timeout-kill-signal.js pins is untouched) and adds a second dispose on 'close', which always fires. Removing an already removed listener is a no-op, so the success path behaves exactly as before

Validation

the test joins test-child-process-spawn-timeout-clear-on-error.js, the file #65506 added

raw output on a pristine main build (the new assertion fails bcs the listener is still attached):

> out/Release/node test/parallel/test-child-process-spawn-timeout-clear-on-error.js
AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:

1 !== 0

    at ChildProcess.<anonymous> (test/parallel/test-child-process-spawn-timeout-clear-on-error.js:34:12)
    at ChildProcess.emit (node:events:514:20)
    ... (truncated, full assertion block in the run log)

Node.js v27.0.0-pre

with the fix (exit code 0, no output), plus the spawn and abort signal files around the change:

test-child-process-spawn-timeout-clear-on-error.js: exit=0
test-child-process-spawn-timeout-kill-signal.js: exit=0
test-child-process-spawn-error.js: exit=0
test-child-process-fork-abort-signal.js: exit=0
test-child-process-exec-abortcontroller-promisified.js: exit=0
test-child-process-execFile-promisified-abortController.js: exit=0
test-child-process-spawnsync-kill-signal.js: exit=0
test-child-process-spawn-controller.js: exit=0

Note: Just to let you knmow that I have used AI assistance to help check the sibling pattern from #65506, but tested and verified all changes locally myself on main build 67a4416