ValueSerializer: promote scheduled exception if the caller throws one.

src/value-serializer.cc

Index: src/value-serializer.cc
diff --git a/src/value-serializer.cc b/src/value-serializer.cc
index 6c3d7e058c2dbf27d35b2b7d2c02ce5faeb55812..d7ce69db1d6e3267d6dc0ddd43f4e9bcd8e68497 100644
--- a/src/value-serializer.cc
+++ b/src/value-serializer.cc
@@ -744,6 +744,9 @@ void ValueSerializer::ThrowDataCloneError(
     isolate_->Throw(
         *isolate_->factory()->NewError(isolate_->error_function(), message));
   }
+  if (isolate_->has_scheduled_exception()) {
+    isolate_->PromoteScheduledException();
+  }
 }
 
 ValueDeserializer::ValueDeserializer(Isolate* isolate,