module: print better message on esm syntax error

Include the offending line in the output and underline the bad token.

Before this commit, it printed "SyntaxError: Unexpected reserved word"
without indicating where the syntax error is.

Now it prints the line and underlines the offending token, like it does
for syntax errors in CJS scripts.

Minor changes are made to the test runner in order to support `*.mjs`
files in test/message.

Fixes: https://github.com/nodejs/node/issues/17277
PR-URL: https://github.com/nodejs/node/pull/17281
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

.eslintignore

@@ -3,6 +3,7 @@ lib/internal/v8_prof_polyfill.js
 lib/punycode.js
 test/addons/??_*
 test/fixtures
+test/message/esm_display_syntax_error.mjs
 tools/eslint
 tools/icu
 tools/remark-*

lib/module.js

@@ -23,6 +23,7 @@
 
 const NativeModule = require('native_module');
 const util = require('util');
+const { decorateErrorStack } = require('internal/util');
 const internalModule = require('internal/module');
 const { getURLFromFilePath } = require('internal/url');
 const vm = require('vm');
@@ -474,6 +475,7 @@ Module._load = function(request, parent, isMain) {
       await ESMLoader.import(getURLFromFilePath(request).pathname);
     })()
     .catch((e) => {
+      decorateErrorStack(e);
       console.error(e);
       process.exit(1);
     });

src/module_wrap.cc

@@ -103,10 +103,18 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
                         False(isolate),                       // is opaque (?)
                         False(isolate),                       // is WASM
                         True(isolate));                       // is ES6 module
+    TryCatch try_catch(isolate);
     ScriptCompiler::Source source(source_text, origin);
-    if (!ScriptCompiler::CompileModule(isolate, &source).ToLocal(&module))
+    if (!ScriptCompiler::CompileModule(isolate, &source).ToLocal(&module)) {
+      CHECK(try_catch.HasCaught());
+      CHECK(!try_catch.Message().IsEmpty());
+      CHECK(!try_catch.Exception().IsEmpty());
+      AppendExceptionLine(env, try_catch.Exception(), try_catch.Message(),
+                          ErrorHandlingMode::MODULE_ERROR);
+      try_catch.ReThrow();
       return;
     }
+  }
 
   Local<Object> that = args.This();
   Local<Context> context = that->CreationContext();

src/node_internals.h

@@ -269,7 +269,7 @@ constexpr size_t arraysize(const T(&)[N]) { return N; }
 
 bool IsExceptionDecorated(Environment* env, v8::Local<v8::Value> er);
 
-enum ErrorHandlingMode { FATAL_ERROR, CONTEXTIFY_ERROR };
+enum ErrorHandlingMode { CONTEXTIFY_ERROR, FATAL_ERROR, MODULE_ERROR };
 void AppendExceptionLine(Environment* env,
                          v8::Local<v8::Value> er,
                          v8::Local<v8::Message> message,

test/fixtures/es-module-loaders/syntax-error.mjs

@@ -0,0 +1,2 @@
+'use strict';
+await async () => 0;

test/message/esm_display_syntax_error.mjs

@@ -0,0 +1,3 @@
+// Flags:  --experimental-modules
+'use strict';
+await async () => 0;

test/message/esm_display_syntax_error.out

@@ -0,0 +1,7 @@
+(node:*) ExperimentalWarning: The ESM module loader is experimental.
+file:///*/test/message/esm_display_syntax_error.mjs:3
+await async () => 0;
+^^^^^
+SyntaxError: Unexpected reserved word
+    at loaders.set (internal/loader/ModuleRequest.js:*:*)
+    at <anonymous>

test/message/esm_display_syntax_error_module.mjs

@@ -0,0 +1,3 @@
+// Flags:  --experimental-modules
+import '../common';
+import '../fixtures/es-module-loaders/syntax-error';

test/message/esm_display_syntax_error_module.out

@@ -0,0 +1,7 @@
+(node:*) ExperimentalWarning: The ESM module loader is experimental.
+file:///*/test/fixtures/es-module-loaders/syntax-error.mjs:2
+await async () => 0;
+^^^^^
+SyntaxError: Unexpected reserved word
+    at loaders.set (internal/loader/ModuleRequest.js:*:*)
+    at <anonymous>

test/message/testcfg.py

@@ -114,7 +114,8 @@ class MessageTestConfiguration(test.TestConfiguration):
 
   def Ls(self, path):
     if isdir(path):
-        return [f[:-3] for f in os.listdir(path) if f.endswith('.js')]
+      return [f for f in os.listdir(path)
+              if f.endswith('.js') or f.endswith('.mjs')]
     else:
       return []
 
@@ -123,9 +124,8 @@ class MessageTestConfiguration(test.TestConfiguration):
     result = []
     for test in all_tests:
       if self.Contains(path, test):
-        file_prefix = join(self.root, reduce(join, test[1:], ""))
-        file_path = file_prefix + ".js"
-        output_path = file_prefix + ".out"
+        file_path = join(self.root, reduce(join, test[1:], ''))
+        output_path = file_path[:file_path.rfind('.')] + '.out'
         if not exists(output_path):
           raise Exception("Could not find %s" % output_path)
         result.append(MessageTestCase(test, file_path, output_path,