From aed08f50762d65500e39c385775c6f9ffca41586 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vin=C3=ADcius=20Louren=C3=A7o?= <contact@viniciusl.com.br>
Date: Mon, 15 Jul 2024 18:27:36 -0300
Subject: [PATCH 1/2] lib: improve error message when index not found on cjs

---
 src/node_file.cc                             | 9 ++-------
 test/es-module/test-cjs-legacyMainResolve.js | 4 ++--
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/node_file.cc b/src/node_file.cc
index c59235b51cca9f..c1590dbfaed1fb 100644
--- a/src/node_file.cc
+++ b/src/node_file.cc
@@ -3149,14 +3149,9 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
     }
   }
 
-  std::optional<std::string> module_path =
-      node::url::FileURLToPath(env, *package_json_url);
+  std::string module_path = *initial_file_path + ".js";
   std::optional<std::string> module_base;
 
-  if (!module_path.has_value()) {
-    return;
-  }
-
   if (args.Length() >= 3 && args[2]->IsString()) {
     Utf8Value utf8_base_path(isolate, args[2]);
     auto base_url =
@@ -3180,7 +3175,7 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
 
   THROW_ERR_MODULE_NOT_FOUND(isolate,
                              "Cannot find package '%s' imported from %s",
-                             *module_path,
+                             module_path,
                              *module_base);
 }
 
diff --git a/test/es-module/test-cjs-legacyMainResolve.js b/test/es-module/test-cjs-legacyMainResolve.js
index 1dc7d8faafe6eb..089455edf655e6 100644
--- a/test/es-module/test-cjs-legacyMainResolve.js
+++ b/test/es-module/test-cjs-legacyMainResolve.js
@@ -129,7 +129,7 @@ describe('legacyMainResolve', () => {
     );
     assert.throws(
       () => legacyMainResolve(packageJsonUrl, { main: null }, packageJsonUrl),
-      { code: 'ERR_MODULE_NOT_FOUND' },
+      { message: /index\.js/, code: 'ERR_MODULE_NOT_FOUND' },
     );
   });
 
@@ -137,7 +137,7 @@ describe('legacyMainResolve', () => {
     const packageJsonUrl = pathToFileURL('/c/file%20with%20percents/package.json');
     assert.throws(
       () => legacyMainResolve(packageJsonUrl, { main: null }, packageJsonUrl),
-      { code: 'ERR_MODULE_NOT_FOUND' },
+      { message: /index\.js/, code: 'ERR_MODULE_NOT_FOUND' },
     );
   });
 

From 6090a922cc7888cbeb890b867908baa4eff92b9b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vin=C3=ADcius=20Louren=C3=A7o?= <contact@viniciusl.com.br>
Date: Tue, 16 Jul 2024 10:04:18 -0300
Subject: [PATCH 2/2] better error message

---
 src/node_file.cc                             | 10 ++++++++--
 test/es-module/test-cjs-legacyMainResolve.js | 13 +++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/node_file.cc b/src/node_file.cc
index c1590dbfaed1fb..f0cccd9c596f25 100644
--- a/src/node_file.cc
+++ b/src/node_file.cc
@@ -3072,6 +3072,8 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
     return;
   }
 
+  std::string package_initial_file = "";
+
   ada::result<ada::url_aggregator> file_path_url;
   std::optional<std::string> initial_file_path;
   std::string file_path;
@@ -3094,6 +3096,8 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
 
     FromNamespacedPath(&initial_file_path.value());
 
+    package_initial_file = *initial_file_path;
+
     for (int i = 0; i < legacy_main_extensions_with_main_end; i++) {
       file_path = *initial_file_path + std::string(legacy_main_extensions[i]);
 
@@ -3149,7 +3153,9 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
     }
   }
 
-  std::string module_path = *initial_file_path + ".js";
+  if (package_initial_file == "")
+    package_initial_file = *initial_file_path + ".js";
+
   std::optional<std::string> module_base;
 
   if (args.Length() >= 3 && args[2]->IsString()) {
@@ -3175,7 +3181,7 @@ void BindingData::LegacyMainResolve(const FunctionCallbackInfo<Value>& args) {
 
   THROW_ERR_MODULE_NOT_FOUND(isolate,
                              "Cannot find package '%s' imported from %s",
-                             module_path,
+                             package_initial_file,
                              *module_base);
 }
 
diff --git a/test/es-module/test-cjs-legacyMainResolve.js b/test/es-module/test-cjs-legacyMainResolve.js
index 089455edf655e6..0bfeb567a22b1f 100644
--- a/test/es-module/test-cjs-legacyMainResolve.js
+++ b/test/es-module/test-cjs-legacyMainResolve.js
@@ -141,6 +141,19 @@ describe('legacyMainResolve', () => {
     );
   });
 
+  it('should report main file on error message when not found', () => {
+    const packageJsonUrl = pathToFileURL(
+      path.resolve(
+        fixtures.path('/es-modules/legacy-main-resolver'),
+        'package.json'
+      )
+    );
+    assert.throws(
+      () => legacyMainResolve(packageJsonUrl, { main: './index.node' }, packageJsonUrl),
+      { message: /index\.node/, code: 'ERR_MODULE_NOT_FOUND' },
+    );
+  });
+
   it('should throw when cannot resolve to a file (base not defined)', () => {
     const packageJsonUrl = pathToFileURL(
       path.resolve(