How to reproduce:
1. Open attached project
2. Open 'Edit while paused' scene
3. Select Human in Inspector
4. In VeryAnimation tab select Focus Animation Window, then Edit Animation
5. In VA Control window Hierarchy select Spine
6. In VA Editor window Selection click anywhere on the Spine Twist Left-Right slider and then undo once (to make sure undo works for Change muscle action)
7. In Animation window Play animation
8. In VA Editor window Selection click anywhere on the same slider and then undo once
9. Observe Console

InvalidOperationException: Sequence contains no elements
System.Linq.Enumerable.Last[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <f1160d35ca3b401a8765abde375a7765>:0)
UnityEditor.Graphs.AnimatorControllerTool.UpdateStateMachineSelection () (at /Users/bokken/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:1012)
UnityEditor.Graphs.AnimatorControllerTool.RebuildGraph (System.Boolean updateSelection) (at /Users/bokken/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:876)
UnityEditor.Graphs.AnimatorControllerTool.UndoRedoPerformed () (at /Users/bokken/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:801)
UnityEditor.Undo.Internal_CallUndoRedoPerformed () (at /Users/bokken/buildslave/unity/build/Editor/Mono/Undo/Undo.bindings.cs:289)

Reproduced with: 2022.1.0a5, 2022.1.0b2
Does not reproduce with: 2021.2.7f1