Add defensive assert for having a weak, empty presistent in a

include/v8-util.h

Index: include/v8-util.h
diff --git a/include/v8-util.h b/include/v8-util.h
index 60feff549d99da5c1c2b76a40a25a40580e0d857..3b4dd486b597b6eb18f60e83e237a755114efa22 100644
--- a/include/v8-util.h
+++ b/include/v8-util.h
@@ -283,6 +283,10 @@ class PersistentValueMap {
    */
   UniquePersistent<V> SetUnique(const K& key, UniquePersistent<V>* persistent) {
     if (Traits::kCallbackType != kNotWeak) {
+      // If the persistent is empty, the weak callback will actually never
+      // happen since there's no object to be garbage collected.
+      RELEASE_ASSERT(!persistent->IsEmpty());

[jochen (gone - plz use gerrit), 2014/05/05 17:42:46]

the v8 equivalent to RELEASE_ASSERT() is CHECK(), however, it's not available in
the header :-/

I'd add the CHECK in GlobalHandles::MakeWeak()

+
       Local<V> value(Local<V>::New(isolate_, *persistent));
       persistent->template SetWeak<typename Traits::WeakCallbackDataType>(
         Traits::WeakCallbackParameter(this, key, value), WeakCallback);