child_process: fix bad abort signal leak

Move abort signal validation to before spawn is executed
so that the file is not leaked.

PR-URL: nodejs#37257
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/child_process.js

@@ -875,11 +875,14 @@ function spawnWithSignal(file, args, options) {
   const opts = options && typeof options === 'object' && ('signal' in options) ?
     { ...options, signal: undefined } :
     options;
-  const child = spawn(file, args, opts);
 
-  if (options && options.signal) {
+  if (options?.signal) {
     // Validate signal, if present
     validateAbortSignal(options.signal, 'options.signal');
+  }
+  const child = spawn(file, args, opts);
+
+  if (options && options.signal) {
     function kill() {
       if (child._handle) {
         child._handle.kill(options.killSignal || 'SIGTERM');