Enter Playmode Settings generates errors

[leissler]

When using the following combo of "Enter Playmode Settings"

a MonoGraphModel on a GameObject throws the following error when the GraphWindow is open and entering Play Mode in the editor:
ArgumentException: Object at index 0 is null
UnityEditor.SerializedObject..ctor (UnityEngine.Object obj) (at /Users/bokken/build/output/unity/unity/Editor/Mono/SerializedObject.bindings.cs:22)
NewGraph.GraphModelBase.CreateSerializedObject (UnityEngine.Object scope, System.String rootFieldName) (at Assets/NewGraph/Models/GraphModelBase.cs:147)
NewGraph.MonoGraphModel.CreateSerializedObject () (at Assets/NewGraph/Models/MonoGraphModel.cs:61)
NewGraph.MonoGraphModel.get_BaseObject () (at Assets/NewGraph/Models/MonoGraphModel.cs:44)
NewGraph.GraphSettings.SetLastOpenedGraphData (NewGraph.IGraphModelData graphData) (at Assets/NewGraph/Editor/Settings/GraphSettings.cs:35)
NewGraph.GraphController+<>c__DisplayClass43_0.b__0 () (at Assets/NewGraph/Editor/Controllers/GraphController.cs:452)
UnityEngine.UIElements.VisualElement+SimpleScheduledItem.PerformTimerUpdate (UnityEngine.UIElements.TimerState state) (at /Users/bokken/build/output/unity/unity/ModuleOverrides/com.unity.ui/Core/VisualElementScheduler.cs:346)
UnityEngine.UIElements.TimerEventScheduler.UpdateScheduledEvents () (at /Users/bokken/build/output/unity/unity/ModuleOverrides/com.unity.ui/Core/Scheduler.cs:363)
UnityEngine.UIElements.UIElementsUtility.UnityEngine.UIElements.IUIElementsUtility.UpdateSchedulers () (at /Users/bokken/build/output/unity/unity/ModuleOverrides/com.unity.ui/Core/UIElementsUtility.cs:253)
UnityEngine.UIElements.UIEventRegistration.UpdateSchedulers () (at /Users/bokken/build/output/unity/unity/ModuleOverrides/com.unity.ui/Core/UIElementsUtility.cs:105)
UnityEditor.RetainedMode.UpdateSchedulers () (at /Users/bokken/build/output/unity/unity/ModuleOverrides/com.unity.ui/Editor/RetainedMode.cs:55)

With a ScriptableGraphModel this works fine and without errors.