module: fix Windows folder exports deprecation warning

PR-URL: https://github.com/nodejs/node/pull/36859
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Geoffrey Booth <webmaster@geoffreybooth.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

lib/internal/modules/esm/resolve.js

@@ -65,12 +65,11 @@ const emittedPackageWarnings = new SafeSet();
 function emitFolderMapDeprecation(match, pjsonUrl, isExports, base) {
   const pjsonPath = fileURLToPath(pjsonUrl);
   if (!pendingDeprecation) {
-    const nodeModulesIndex = StringPrototypeLastIndexOf(pjsonPath,
-                                                        '/node_modules/');
+    const nodeModulesIndex =
+        StringPrototypeLastIndexOf(pjsonPath, sep + 'node_modules' + sep);
     if (nodeModulesIndex !== -1) {
-      const afterNodeModulesPath = StringPrototypeSlice(pjsonPath,
-                                                        nodeModulesIndex + 14,
-                                                        -13);
+      const afterNodeModulesPath =
+          StringPrototypeSlice(pjsonPath, nodeModulesIndex + 14, -13);
       try {
         const { packageSubpath } = parsePackageName(afterNodeModulesPath);
         if (packageSubpath === '.')

test/es-module/test-esm-local-deprecations.mjs

@@ -6,6 +6,9 @@ import { pathToFileURL } from 'url';
 const selfDeprecatedFolders =
     fixtures.path('/es-modules/self-deprecated-folders/main.js');
 
+const deprecatedFoldersIgnore =
+    fixtures.path('/es-modules/deprecated-folders-ignore/main.js');
+
 let curWarning = 0;
 const expectedWarnings = [
   '"./" in the "exports" field',
@@ -18,5 +21,6 @@ process.addListener('warning', mustCall((warning) => {
 
 (async () => {
   await import(pathToFileURL(selfDeprecatedFolders));
+  await import(pathToFileURL(deprecatedFoldersIgnore));
 })()
 .catch((err) => console.error(err));

test/fixtures/es-modules/deprecated-folders-ignore/main.js

@@ -0,0 +1 @@
+import 'pkg/folder/m.js';

test/fixtures/es-modules/deprecated-folders-ignore/node_modules/pkg/m.js

@@ -0,0 +1 @@
+export default null;

test/fixtures/es-modules/deprecated-folders-ignore/node_modules/pkg/package.json

@@ -0,0 +1,7 @@
+{
+  "exports": {
+    "./folder/": "./"
+  },
+  "type": "module"
+}
+

test/fixtures/es-modules/deprecated-folders-ignore/package.json

@@ -0,0 +1,4 @@
+{
+  "type": "module"
+}
+