I updated a project from Unity 2021.1 to 2021.2 (beta) and now Map Magic gives a null reference error:
NullReferenceException: Object reference not set to an instance of an object
Den.Tools.Serialization.Serializer.SerializeRecursive (System.String name, System.Object val, System.Collections.Generic.Dictionary`2[TKey,TValue] serializedObjsIds, System.Collections.Generic.List`1[T] unityObjs, System.String offset) (at Assets/MapMagic/Tools/Serializer/Serialize.cs:218)
Den.Tools.Serialization.Serializer.SerializeRecursive (System.String name, System.Object val, System.Collections.Generic.Dictionary`2[TKey,TValue] serializedObjsIds, System.Collections.Generic.List`1[T] unityObjs, System.String offset) (at Assets/MapMagic/Tools/Serializer/Serialize.cs:218)
Den.Tools.Serialization.Serializer.Serialize (System.Object val, UnityEngine.Object[]& unityObjs) (at Assets/MapMagic/Tools/Serializer/Serialize.cs:64)
MapMagic.Expose.Override.OnBeforeSerialize () (at Assets/MapMagic/Expose/Override.cs:244)
Den.Tools.Serializer.SerializeObject (System.Object obj, System.Collections.Generic.Dictionary`2[TKey,TValue] serialized, System.Boolean skipNoCopyAttribute, System.Action`2[T1,T2] onAfterSerialize) (at Assets/MapMagic/Tools/Serializer.cs:379)
Den.Tools.Serializer.SerializeObject (System.Object obj, System.Collections.Generic.Dictionary`2[TKey,TValue] serialized, System.Boolean skipNoCopyAttribute, System.Action`2[T1,T2] onAfterSerialize) (at Assets/MapMagic/Tools/Serializer.cs:422)
Den.Tools.Serializer.Serialize (System.Object obj, System.Action`2[T1,T2] onAfterSerialize) (at Assets/MapMagic/Tools/Serializer.cs:177)
MapMagic.Nodes.GraphSerializer200Beta.Serialize (MapMagic.Nodes.Graph graph) (at Assets/MapMagic/Nodes/GraphSerializer.cs:53)
MapMagic.Nodes.Graph.OnBeforeSerialize () (at Assets/MapMagic/Nodes/Graph.cs:1149)