child_process: release the abort listener when a spawn fails

A failed spawn emits 'error' and 'close' but never 'exit'. The
AbortSignal cleanup in spawn() was registered on 'exit', so the abort
listener stayed attached to the user's signal after a failed spawn.

Register the cleanup on 'close' as well, matching the timeout cleanup.

Signed-off-by: Abdel <hktitof@gmail.com>

Author: hktitof

lib/child_process.js

@@ -919,7 +919,10 @@ function spawn(file, args, options) {
     } else {
       addAbortListener ??= require('internal/events/abort_listener').addAbortListener;
       const disposable = addAbortListener(signal, onAbortListener);
+      // 'exit' does not fire when the spawn itself fails, so the listener
+      // is also released on 'close', which always fires.
       child.once('exit', disposable[SymbolDispose]);
+      child.once('close', disposable[SymbolDispose]);
     }
 
     function onAbortListener() {

test/parallel/test-child-process-spawn-timeout-clear-on-error.js

@@ -4,6 +4,9 @@
 // The outer spawnSync timeout catches a leaked inner timer.
 
 const common = require('../common');
+const assert = require('node:assert');
+const { getEventListeners } = require('node:events');
+const { spawn } = require('node:child_process');
 const { spawnSyncAndExitWithoutError } = require('../common/child_process');
 
 const bugStallMs = common.platformTimeout(10000);
@@ -17,3 +20,17 @@ spawnSyncAndExitWithoutError(process.execPath, ['-e', `
   });
   cp.on('error', () => {});
 `], { timeout: outerTimeoutMs });
+
+// A failed spawn never emits 'exit'. The abort listener must be gone by
+// the time 'close' fires, or it stays attached to the user's signal.
+{
+  const controller = new AbortController();
+  const cp = spawn(process.execPath, ['--version'], {
+    cwd: '/nonexistent/path/that/should/never/exist',
+    signal: controller.signal,
+  });
+  cp.on('error', () => {});
+  cp.on('close', common.mustCall(() => {
+    assert.strictEqual(getEventListeners(controller.signal, 'abort').length, 0);
+  }));
+}