错误：
Self referencing loop detected for property 'normalized' with type 'UnityEngine.Vector3'. Path '[0].coor'.

错误原因：

NewtonSoft has a hard time serializing structs (Vector3 is defined as a struct). More specifically that struct has a property normalized that actually returns a Vector3 also, that Vector3 also has a normalized property and so on, so what happens is NewtonSoft is trying to serialize that new Vector3 everytime and you end up in an infinite loop.
 

解决方案1：
My workaround for this was to create a custom class for this purpose:

[System.Serializable]
public class SerializableVector3{
    public float x;
    public float y;
    public float z;
 
    [JsonIgnore]
    public Vector3 UnityVector{
        get{
            return new Vector3(x, y, z);
        }
    }
 
    public SerializableVector3(Vector3 v){
        x = v.x;
        y = v.y;
        z = v.z;
    }
 
    public static List<SerializableVector3> GetSerializableList(List<Vector3> vList){
        List<SerializableVector3> list = new List<SerializableVector3>(vList.Count);
        for(int i = 0 ; i < vList.Count ; i++){
            list.Add(new SerializableVector3(vList[i]));
        }
        return list;
    }
 
    public static List<Vector3> GetSerializableList(List<SerializableVector3> vList){
        List<Vector3> list = new List<Vector3>(vList.Count);
        for(int i = 0 ; i < vList.Count ; i++){
            list.Add(vList[i].UnityVector);
        }
        return list;
    }
}

Whenever you serialize a class make sure to convert all your Vector3 to SerializableVector3 and vice-versa when you deserialize. I use the ISerializable interface (System.Runtime.Serialization) for this purpose among other things.

JsonSerializationException: Self referencing loop detected - Unity Forum

解决方案2：

ReferenceLoopHandling setting