update spawnSync for npm run test

In windows platform, the `spawnSync` will fail without explicitly
invoking the `cmd.exe` to run a bat script. When the `spawnSync` failed,
the `stdout` and `stderr` will be undefined. Added protection for them.

Bug: 490139146
Change-Id: Ib744a36c9a81a2bf5b20dae3689acc6b057cad05
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7640129
Commit-Queue: Guangyue Xu <guangyue.xu@microsoft.com>
Reviewed-by: Nikolay Vitkov <nvitkov@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>

Author: guangyuexu

scripts/run_on_target.mjs

@@ -81,14 +81,20 @@ if (
 }
 
 if (!skipNinja) {
+  const ninjaCommand = process.platform === 'win32' ? process.env.ComSpec ?? 'cmd.exe' : 'autoninja';
+  const ninjaArgs = process.platform === 'win32' ? ['/c', 'autoninja', '-C', cwd, script] : ['-C', cwd, script];
   const { error, status, stdout, stderr } = childProcess.spawnSync(
-    'autoninja',
-    ['-C', cwd, script],
+    ninjaCommand,
+    ninjaArgs,
     { stdio: debug ? 'inherit' : 'pipe', cwd: sourceRoot },
   );
   if (status || error) {
-    console.log(stdout.toString());
-    console.log(stderr.toString());
+    if (stdout) {
+      console.log(stdout.toString());
+    }
+    if (stderr) {
+      console.log(stderr.toString());
+    }
     if (error) {
       console.error(error);
     }