This is what I get now, running the filters example scope:

#
# Fatal error in ../deps/v8/src/api.h, line 412
# Check failed: that == __null || (*reinterpret_cast<v8::internal::Object* const*>(that))->IsJSObject().
#

==== C stack trace ===============================

 1: V8_Fatal
 2: v8::Utils::OpenHandle(v8::Object const*, bool)
 3: v8::Object::Has(v8::Local<v8::Value>)
 4: ValueSliderLabels::ValueSliderLabels(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, v8::Local<v8::Value>)
 5: ValueSliderLabels* v8cpp::internal::ObjectFactory<ValueSliderLabels>::new_object<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value> >(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>)
 6: v8cpp::internal::FunctionTraits<ValueSliderLabels* (*)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>)>::ReturnType v8cpp::internal::call_from_v8_impl<ValueSliderLabels* (*)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>), 0ul, 1ul, 2ul>(ValueSliderLabels* (*&&)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>), v8::FunctionCallbackInfo<v8::Value> const&, v8cpp::internal::CallFromV8Traits<ValueSliderLabels* (*)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>), 1ul>, v8cpp::internal::IntSequence<unsigned long, 0ul, 1ul, 2ul>)
 7: v8cpp::internal::FunctionTraits<ValueSliderLabels* (*)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>)>::ReturnType v8cpp::internal::call_from_v8<ValueSliderLabels* (*)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>)>(ValueSliderLabels* (*&&)(v8::Isolate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value>), v8::FunctionCallbackInfo<v8::Value> const&)
 8: void v8cpp::internal::Class<ValueSliderLabels>::set_constructor<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value> >()::{lambda(v8::FunctionCallbackInfo<v8::Value> const&)#1}::operator()(v8::FunctionCallbackInfo<v8::Value> const&) const
 9: std::_Function_handler<ValueSliderLabels* (v8::FunctionCallbackInfo<v8::Value> const&), void v8cpp::internal::Class<ValueSliderLabels>::set_constructor<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, v8::Local<v8::Value> >()::{lambda(v8::FunctionCallbackInfo<v8::Value> const&)#1}>::_M_invoke(std::_Any_data const&, v8::FunctionCallbackInfo<v8::Value> const&)
10: std::function<ValueSliderLabels* (v8::FunctionCallbackInfo<v8::Value> const&)>::operator()(v8::FunctionCallbackInfo<v8::Value> const&) const
11: v8cpp::internal::Class<ValueSliderLabels>::export_object(v8::FunctionCallbackInfo<v8::Value> const&)
12: v8cpp::internal::Class<ValueSliderLabels>::Class(v8::Isolate*, unsigned long)::{lambda(v8::FunctionCallbackInfo<v8::Value> const&)#1}::operator()(v8::FunctionCallbackInfo<v8::Value> const&) const
13: v8cpp::internal::Class<ValueSliderLabels>::Class(v8::Isolate*, unsigned long)::{lambda(v8::FunctionCallbackInfo<v8::Value> const&)#1}::_FUN(v8::FunctionCallbackInfo<v8::Value> const&)
14: v8::internal::FunctionCallbackArguments::Call(void (*)(v8::FunctionCallbackInfo<v8::Value> const&))
15: 0xeaeb0c
16: 0xea7f0c
17: 0xea7e5a
18: 0x2f4f091060bb