Error on deleting layer in Animator Controller

2) How can we reproduce it using the example you attached
1 Create new project
2 Create New Animator Controller and open it (you should be on the "Base layer")
3 Add one more layer (" "-button)
4 Delete this new created layer

Actual result: notice error in console

MissingReferenceException: The object of type 'AnimatorStateMachine' has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.
UnityEditor.Animations.AnimatorStateMachine.get_anyStatePosition () (at C:/buildslave/unity/build/artifacts/generated/common/editor/StateMachineBindings.gen.cs:400)
UnityEditor.Graphs.AnimationStateMachine.Graph.ReadAnyStatePosition (UnityEditor.Graphs.AnimationStateMachine.AnyStateNode anyStateNode) (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/AnimationStateMachine/Graph.cs:513)
UnityEditor.Graphs.AnimationStateMachine.Graph.ReadNodePositions () (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/AnimationStateMachine/Graph.cs:507)
UnityEditor.Graphs.AnimatorControllerTool.ControllerDirty () (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:222)
UnityEditor.Animations.AnimatorController.OnInvalidateAnimatorController (UnityEditor.Animations.AnimatorController controller) (at C:/buildslave/unity/build/Editor/Mono/Animation/AnimatorController.cs:34)
UnityEditor.DockArea:OnGUI()