Reference loop => JSON.NET 5.0.6

`IgnoreEnumerableReferenceLoop` fails before JSON.NET upgrade.

I also wonder if it makes sense to set `JsonNetSerializer.Settings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore`, since you're really just serializing for informational purposes. It doesn't really seem (to me) that it's an "error" worth reporting.