message: Fix broken GetInt64.
diff: @@ -180,7 +180,8 @@ int64 FCesiumMetadataGenericValue::GetInt64() const {
  return std::visit(
  [](const auto& v) -> int64_t {
  - if constexpr (CesiumGltf::IsMetadataNumeric<decltype(v)>::value) {
  + using CoreType = std::remove_cv_t<std::remove_reference_t<decltype(v)>>;
  + if constexpr (CesiumGltf::IsMetadataNumeric<CoreType>::value) {
  return static_cast<int64_t>(v);
  }
  