If an unhandled exception occurs in Dart_RunLoop, pass it out to the caller.

runtime/lib/isolate.cc

 // Copyright (c) 2011, 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 "vm/bootstrap_natives.h"
 
 #include "vm/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
@@ skipping 145 matching lines @@
     // Lookup the target class by name, create an instance and call the run
     // method.
     const String& lib_name = String::Handle(String::NewSymbol(library_url));
     const Library& lib = Library::Handle(Library::LookupLibrary(lib_name));
     ASSERT(!lib.IsNull());
     const String& cls_name = String::Handle(String::NewSymbol(class_name));
     const Class& target_class = Class::Handle(lib.LookupClass(cls_name));
     // TODO(iposva): Deserialize or call the constructor after allocating.
     // For now, we only support a non-parameterized or raw target class.
     const Instance& target = Instance::Handle(Instance::New(target_class));
-    Instance& result = Instance::Handle();
+    Object& result = Object::Handle();
 
     // Invoke the default constructor.
     const String& period = String::Handle(String::New("."));
     String& constructor_name = String::Handle(String::Concat(cls_name, period));
     const Function& default_constructor =
         Function::Handle(target_class.LookupConstructor(constructor_name));
     if (!default_constructor.IsNull()) {
       GrowableArray<const Object*> arguments(1);
       arguments.Add(&target);
       arguments.Add(&Smi::Handle(Smi::New(Function::kCtorPhaseAll)));
@@ skipping 23 matching lines @@
                                       target_function,
                                       arguments,
                                       kNoArgumentNames);
     if (result.IsUnhandledException()) {
       UnhandledException& uhe = UnhandledException::Handle();
       uhe ^= result.raw();
       ProcessUnhandledException(uhe);
     }
     ASSERT(result.IsNull());
     free(class_name);
-    isolate->StandardRunLoop();
+    result = isolate->StandardRunLoop();
+    if (result.IsUnhandledException()) {
+      UnhandledException& uhe = UnhandledException::Handle();
+      uhe ^= result.raw();
+      ProcessUnhandledException(uhe);
+    }
+    ASSERT(result.IsNull());
 
   } else {
     Zone zone(isolate);
     HandleScope handle_scope(isolate);
     const String& error = String::Handle(
         Isolate::Current()->object_store()->sticky_error());
     const char* errmsg = error.ToCString();
     fprintf(stderr, "%s\n", errmsg);
     exit(255);
   }
@@ skipping 118 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