child_process: clear timeout timer on spawn-time error too

When spawn() fails at the OS level (ENOENT, EACCES, EAGAIN, EMFILE,
ENFILE), the resulting ChildProcess only ever emits 'error', never
'exit'. The `timeout` option's cleanup only listened for 'exit', so
the timer stayed armed for the full `timeout` duration on any
spawn-time failure, holding the event loop open well after the
promise/callback had already settled via 'error'.

Clear the timer on 'error' as well as 'exit'.

Fixes: https://github.com/nodejs/node/issues/65504
Signed-off-by: kishore280 <maheshwarankishore@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/65506
Reviewed-By: Aviv Keller <me@aviv.sh>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

lib/child_process.js

@@ -824,7 +824,8 @@ function spawn(file, args, options) {
       }
     }, options.timeout);
 
-    child.once('exit', () => {
+    // 'close' always fires after 'exit', or after 'error' on a spawn failure.
+    child.once('close', () => {
       if (timeoutId) {
         clearTimeout(timeoutId);
         timeoutId = null;

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

@@ -0,0 +1,19 @@
+'use strict';
+
+// Measures the child's actual exit time, not just its 'error' event.
+// The outer spawnSync timeout catches a leaked inner timer.
+
+const common = require('../common');
+const { spawnSyncAndExitWithoutError } = require('../common/child_process');
+
+const bugStallMs = common.platformTimeout(10000);
+const outerTimeoutMs = common.platformTimeout(2000);
+
+spawnSyncAndExitWithoutError(process.execPath, ['-e', `
+  const { spawn } = require('child_process');
+  const cp = spawn(process.execPath, ['--version'], {
+    cwd: '/nonexistent/path/that/should/never/exist',
+    timeout: ${bugStallMs},
+  });
+  cp.on('error', () => {});
+`], { timeout: outerTimeoutMs });