Make the "sticky error" an Error instead of a String.

runtime/lib/isolate.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 187 matching lines @@
     free(class_name);
     result = isolate->StandardRunLoop();
     if (result.IsError()) {
       ProcessError(result);
     }
     ASSERT(result.IsNull());
 
   } else {
     Zone zone(isolate);
     HandleScope handle_scope(isolate);
-    const String& error = String::Handle(
+    const Error& error = Error::Handle(
         Isolate::Current()->object_store()->sticky_error());
-    const char* errmsg = error.ToCString();
+    const char* errmsg = error.ToErrorCString();
     OS::PrintErr("%s\n", errmsg);
     exit(255);
   }
   isolate->set_long_jump_base(base);
   Dart::ShutdownIsolate();
 }
 
 
 static bool CheckArguments(const char* library_url, const char* class_name) {
   Isolate* isolate = Isolate::Current();
   Zone zone(isolate);
   HandleScope handle_scope(isolate);
   String& name = String::Handle();
   if (!ClassFinalizer::FinalizePendingClasses()) {
     return false;
   }
   // Lookup the target class by name, create an instance and call the run
   // method.
   name ^= String::NewSymbol(library_url);
   const Library& lib = Library::Handle(Library::LookupLibrary(name));
   if (lib.IsNull()) {
-    const String& error = String::Handle(
+    const String& error_str = String::Handle(
         String::New("Error starting Isolate, library not loaded : "));
+    const Error& error = Error::Handle(LanguageError::New(error_str));
     Isolate::Current()->object_store()->set_sticky_error(error);
     return false;
   }
   name ^= String::NewSymbol(class_name);
   const Class& target_class = Class::Handle(lib.LookupClass(name));
   if (target_class.IsNull()) {
-    const String& error = String::Handle(
+    const String& error_str = String::Handle(
         String::New("Error starting Isolate, class not loaded : "));
+    const Error& error = Error::Handle(LanguageError::New(error_str));
     Isolate::Current()->object_store()->set_sticky_error(error);
     return false;
   }
   return true;  // No errors.
 }
 
 
 DEFINE_NATIVE_ENTRY(IsolateNatives_start, 2) {
   Isolate* preserved_isolate = Isolate::Current();
   const Instance& runnable = Instance::CheckedHandle(arguments->At(0));
@@ skipping 26 matching lines @@
       new Thread(RunIsolate, data);
     } else {
       // Error spawning the isolate, maybe due to initialization errors or
       // errors while loading the application into spawned isolate, shut
       // it down and report error.
       // Make sure to grab the error message out of the isolate before it has
       // been shutdown and to allocate it in the preserved isolates zone.
       {
         Zone zone(spawned_isolate);
         HandleScope scope(spawned_isolate);
-        const String& errmsg = String::Handle(
+        const Error& err_obj = Error::Handle(
             spawned_isolate->object_store()->sticky_error());
-        error = strdup(errmsg.ToCString());
+        error = strdup(err_obj.ToErrorCString());
       }
       Dart::ShutdownIsolate();
       spawned_isolate = NULL;
     }
   }
 
   // Switch back to the original isolate and return.
   Isolate::SetCurrent(preserved_isolate);
   if (spawned_isolate == NULL) {
     // Unable to spawn isolate correctly, throw exception.
@@ skipping 35 matching lines @@
   intptr_t send_id = Smi::CheckedHandle(arguments->At(0)).Value();
   intptr_t reply_id = Smi::CheckedHandle(arguments->At(1)).Value();
   // TODO(iposva): Allow for arbitrary messages to be sent.
   uint8_t* data = SerializeObject(Instance::CheckedHandle(arguments->At(2)));
 
   // TODO(turnidge): Throw an exception when the return value is false?
   PortMap::PostMessage(send_id, reply_id, Api::CastMessage(data));
 }
 
 }  // namespace dart