Editor Crashes on hitting "Undo" while recording animation in the timeline

Steps to Repro:
1. Open attached or create a new project
2. Hierarchy > right click
3. 3D object > cube
4. Window > sequencing > Timeline
5. Select the cube and hit create in timeline window
6. Hit record next to Cube animation track in the timeline window
7. Move the cube to generate a keyframe
8. Hit Undo

Actual Result:
Editor Crashes

Occurring with:
2018.3.0a6, 2018.3.0a5, 2018.3.0a1

Working with:
2018.3.0a1

Environment:
Windows and Mac

Stack Trace:
Assertion failed on expression: 'm_InstanceID != InstanceID_None'
UnityEngine.Animator:Rebind(Animator, Boolean)
UnityEngine.Animator:Rebind() (at C:\buildslave\unity\build\Runtime\Animation\ScriptBindings\Animator.bindings.cs:1195)
UnityEditor.Timeline.WindowState:RebindAnimators() (at C:\buildslave\unity\build\Extensions\Timeline\Editor\State\WindowState.cs:862)
UnityEditor.Timeline.TimelineWindow:OnUndoRedo() (at C:\buildslave\unity\build\Extensions\Timeline\Editor\Window\TimelineWindow_EditorCallbacks.cs:170)
UnityEditor.Undo:Internal_CallUndoRedoPerformed() (at C:\buildslave\unity\build\Editor\Mono\Undo\Undo.bindings.cs:202)

[c:\buildslave\unity\build\runtime\baseclasses\BaseObject.h line 379]
(Filename: C:/buildslave/unity/build/Runtime/Animation/ScriptBindings/Animator.bindings.cs Line: 1195)