Hi
Version 3.8.8.1 Pro (yes, I have local changes I haven’t yet found the time to update with).
I started seeing the error in the title when my custom GridGraph had multiple entries in an array of objects that it opted in to JSON serialization.
I traced the problem down to a bug in TinyJson.cs where Deserialize() decodes List and array. After ls.Add(Deserialize(tp.GetElementType())); there should be a TryEat(','); otherwise having more than one list/array members will throw error: Exception: Expected '{' found ','
HTH, R.