handle_wrap: guard against uninitialized handle or double close

src/handle_wrap.cc

@@ -99,9 +99,11 @@ Handle<Value> HandleWrap::Close(const Arguments& args) {
 
   UNWRAP
 
+  // guard against uninitialized handle or double close
+  if (wrap->handle__ == NULL) return v8::Null();
   assert(!wrap->object_.IsEmpty());
   uv_close(wrap->handle__, OnClose);
-
+  wrap->handle__ = NULL;
 
   HandleWrap::Ref(args);
 
@@ -143,6 +145,9 @@ void HandleWrap::OnClose(uv_handle_t* handle) {
   // The wrap object should still be there.
   assert(wrap->object_.IsEmpty() == false);
 
+  // But the handle pointer should be gone.
+  assert(wrap->handle__ == NULL);
+
   wrap->object_->SetPointerInInternalField(0, NULL);
   wrap->object_.Dispose();
   wrap->object_.Clear();