Adding New Script to Animation State causes editor to throw NullReferenceException, Refer attached video

Steps to repro:
Create a new Project
Project > right-click > Create > Animator Controller > Open
Animator Blackboard > right-click > Create State > Empty
Select "New State"
Inspector > Add Behaviour > New Script > Enter Name > Create and Add

Actual Result:
NullReferenceException errors are thrown in the console on adding New Script to Animation State.

Expected Result:
New script is added to Animation State without any exceptions

Reproducible in:
2020.1.0a13, 2020.1.0a4

Working Fine in:
2020.1.0a3, 2019.3.0b11.

Environment:
Windows 10 & macOS 10.14.

Stack trace:
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Graphs.AnimationStateMachine.StateMachineBehaviorsEditor.BuildEditorList (UnityEngine.StateMachineBehaviour[] behaviours) (at <fbf7b765d0734eb5a695036ccdd28df5>:0)
UnityEditor.Graphs.AnimationStateMachine.StateMachineBehaviorsEditor.OnInspectorGUI () (at <fbf7b765d0734eb5a695036ccdd28df5>:0)
UnityEditor.Graphs.AnimationStateMachine.StateEditor.OnInspectorGUI () (at <fbf7b765d0734eb5a695036ccdd28df5>:0)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass55_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <c68d6dc296e3436796126be8249ff304>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)