ModuleSystem should not crash when JS has a syntax error.

chrome/renderer/module_system.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/module_system.h"
 
 #include "base/bind.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebScopedMicrotaskSuppression.h"
 
 namespace {
 
 const char* kModuleSystem = "module_system";
 const char* kModuleName = "module_name";
 const char* kModuleField = "module_field";
 
+void DumpException(v8::Handle<v8::Message> message) {
+  LOG(ERROR) << "["
+             << *v8::String::Utf8Value(
+                 message->GetScriptResourceName()->ToString())
+             << "(" << message->GetLineNumber() << ")] "
+             << *v8::String::Utf8Value(message->Get());
+}
+
 } // namespace
 
 ModuleSystem::ModuleSystem(SourceMap* source_map)
     : source_map_(source_map),
       natives_enabled_(0) {
   RouteFunction("require",
       base::Bind(&ModuleSystem::RequireForJs, base::Unretained(this)));
   RouteFunction("requireNative",
       base::Bind(&ModuleSystem::GetNative, base::Unretained(this)));
 
@@ skipping 28 matching lines @@
 
 v8::Handle<v8::Value> ModuleSystem::RequireForJsInner(
     v8::Handle<v8::String> module_name) {
   v8::HandleScope handle_scope;
   v8::Handle<v8::Object> global(v8::Context::GetCurrent()->Global());
   v8::Handle<v8::Object> modules(v8::Handle<v8::Object>::Cast(
       global->GetHiddenValue(v8::String::New("modules"))));
   v8::Handle<v8::Value> exports(modules->Get(module_name));
   if (!exports->IsUndefined())
     return handle_scope.Close(exports);
+
   v8::Handle<v8::Value> source(GetSource(module_name));
   if (source->IsUndefined())
     return handle_scope.Close(v8::Undefined());
   v8::Handle<v8::String> wrapped_source(WrapSource(
       v8::Handle<v8::String>::Cast(source)));
   v8::Handle<v8::Function> func =
       v8::Handle<v8::Function>::Cast(RunString(wrapped_source, module_name));
+  if (func.IsEmpty())
+    return handle_scope.Close(v8::Handle<v8::Value>());
+
   exports = v8::Object::New();
   v8::Handle<v8::Object> natives(NewInstance());
   v8::Handle<v8::Value> args[] = {
     natives->Get(v8::String::NewSymbol("require")),
     natives->Get(v8::String::NewSymbol("requireNative")),
     exports,
   };
   {
     WebKit::WebScopedMicrotaskSuppression suppression;
     func->Call(global, 3, args);
@@ skipping 24 matching lines @@
       parameters->Get(v8::String::New(kModuleSystem));
   ModuleSystem* module_system = static_cast<ModuleSystem*>(
       v8::Handle<v8::External>::Cast(module_system_value)->Value());
 
   v8::Handle<v8::Object> module;
   {
     NativesEnabledScope scope(module_system);
     module = module_system->RequireForJsInner(
         parameters->Get(v8::String::New(kModuleName))->ToString())->ToObject();
   }
+  if (module.IsEmpty())
+    return handle_scope.Close(v8::Handle<v8::Value>());
 
   v8::Handle<v8::String> field =
       parameters->Get(v8::String::New(kModuleField))->ToString();
 
   return handle_scope.Close(module->Get(field));
 }
 
 void ModuleSystem::SetLazyField(v8::Handle<v8::Object> object,
                                 const std::string& field,
                                 const std::string& module_name,
                                 const std::string& module_field) {
   v8::HandleScope handle_scope;
   v8::Handle<v8::Object> parameters = v8::Object::New();
   parameters->Set(v8::String::New(kModuleName),
                   v8::String::New(module_name.c_str()));
   parameters->Set(v8::String::New(kModuleField),
                   v8::String::New(module_field.c_str()));
   parameters->Set(v8::String::New(kModuleSystem), v8::External::New(this));
 
   object->SetAccessor(v8::String::New(field.c_str()),
                       &ModuleSystem::LazyFieldGetter,
                       NULL,
                       parameters);
 }
 
 v8::Handle<v8::Value> ModuleSystem::RunString(v8::Handle<v8::String> code,
                                               v8::Handle<v8::String> name) {
   v8::HandleScope handle_scope;
   WebKit::WebScopedMicrotaskSuppression suppression;
-  return handle_scope.Close(v8::Script::New(code, name)->Run());
+  v8::Handle<v8::Value> result;
+  v8::TryCatch try_catch;
+  try_catch.SetCaptureMessage(true);
+  v8::Handle<v8::Script> script(v8::Script::New(code, name));
+  if (try_catch.HasCaught()) {
+    DumpException(try_catch.Message());
+    return handle_scope.Close(result);
+  }
+
+  result = script->Run();
+  if (try_catch.HasCaught())
+    DumpException(try_catch.Message());
+
+  return handle_scope.Close(result);
 }
 
 v8::Handle<v8::Value> ModuleSystem::GetSource(
     v8::Handle<v8::String> source_name) {
   v8::HandleScope handle_scope;
   std::string module_name = *v8::String::AsciiValue(source_name);
   if (!source_map_->Contains(module_name))
     return v8::Undefined();
   return handle_scope.Close(source_map_->GetSource(module_name));
 }
@@ skipping 14 matching lines @@
   v8::Handle<v8::String> left =
       v8::String::New("(function(require, requireNative, exports) {");
   v8::Handle<v8::String> right = v8::String::New("\n})");
   return handle_scope.Close(
       v8::String::Concat(left, v8::String::Concat(source, right)));
 }
 
 v8::Handle<v8::Value> ModuleSystem::ThrowException(const std::string& message) {
   return v8::ThrowException(v8::String::New(message.c_str()));
 }