Steps to reproduce:
1. Create new Unity project
2. Open Package Manager window and install Entities package
3. Open Entities Hierarchy window (Window > Entities > Entities Hierarchy)
4. Create a New Subscene in Entities Hierarchy window
5. Create 2 Cubes in newly created Subscene in Entities Hierarchy window
6. Undo Cube creation (undo 4-5 times with keyboard shortcut)
7. Observe the Console window

Actual results: “IndexOutOfRangeException” error is thrown in the Console window after undoing Cube creation in Entities Hierarchy window

Expected results: No errors are throw in the Console after undoing Cube creation in Entities Hierarchy window

Reproducible with versions: 6000.0.72f1, 6000.3.12f1, 6000.4.1f1, 6000.5.0b1
Not reproducible with versions: 6000.6.0a1

Tested on (OS): macOS Silicon Tahoe 26.3.1 (a) (M1)

Notes:

{code:java}
IndexOutOfRangeException: Index 6 is out of range in container of '6' Length.
Unity.Collections.CollectionHelper.CheckIndexInRange (System.Int32 index, System.Int32 length) (at ./Library/PackageCache/com.unity.collections@12999e356c23/Unity.Collections/CollectionHelper.cs:300)
Unity.Collections.LowLevel.Unsafe.UnsafeList`1[T].get_Item (System.Int32 index) (at ./Library/PackageCache/com.unity.collections@12999e356c23/Unity.Collections/UnsafeList.cs:133)
Unity.Collections.NativeList`1[T].get_Item (System.Int32 index) (at ./Library/PackageCache/com.unity.collections@12999e356c23/Unity.Collections/NativeList.cs:156)
Unity.Entities.Editor.HierarchyNodes.get_Item (System.Int32 index) (at ./Library/PackageCache/com.unity.entities@8b72e8a7d7d1/Unity.Entities.Editor/Hierarchy/Model/HierarchyNodes.cs:106)
Unity.Entities.Editor.HierarchyElement.OnKeyDown (UnityEngine.UIElements.KeyDownEvent evt) (at ./Library/PackageCache/com.unity.entities@8b72e8a7d7d1/Unity.Entities.Editor/Hierarchy/Controls/HierarchyElement.cs:379)
UnityEngine.UIElements.EventCallbackFunctor`1[TEventType].Invoke (UnityEngine.UIElements.EventBase evt) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventCallback.cs:64)
UnityEngine.UIElements.EventCallbackRegistry+DynamicCallbackList.Invoke (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel, UnityEngine.UIElements.VisualElement target) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventCallbackRegistry.cs:246)
UnityEngine.UIElements.EventDispatchUtilities.HandleEvent_BubbleUpCallbacks (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel, UnityEngine.UIElements.VisualElement element) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventDispatchUtilities.cs:405)
UnityEngine.UIElements.EventDispatchUtilities.HandleEventAcrossPropagationPath (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel, UnityEngine.UIElements.VisualElement target, System.Boolean isCapturingTarget) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventDispatchUtilities.cs:212)
UnityEngine.UIElements.EventDispatchUtilities.PropagateEvent (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel, UnityEngine.UIElements.VisualElement target, System.Boolean isCapturingTarget) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventDispatchUtilities.cs:70)
UnityEngine.UIElements.EventDispatchUtilities.DispatchToFocusedElementOrPanelRoot (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/EventDispatchUtilities.cs:509)
UnityEngine.UIElements.KeyboardEventBase`1[T].Dispatch (UnityEngine.UIElements.BaseVisualElementPanel panel) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Events/KeyboardEvents.cs:265)
UnityEngine.UIElements.EventDispatcher.ProcessEvent (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/EventDispatcher.cs:419)
UnityEngine.UIElements.EventDispatcher.Dispatch (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.BaseVisualElementPanel panel, UnityEngine.UIElements.DispatchMode dispatchMode) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/EventDispatcher.cs:215)
UnityEngine.UIElements.BaseVisualElementPanel.SendEvent (UnityEngine.UIElements.EventBase e, UnityEngine.UIElements.DispatchMode dispatchMode) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/Panel.cs:677)
UnityEngine.UIElements.UIElementsUtility.DoDispatch (UnityEngine.UIElements.BaseVisualElementPanel panel) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UIElementsUtility.cs:545)
UnityEngine.UIElements.UIElementsUtility.UnityEngine.UIElements.IUIElementsUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr, System.Boolean& eventHandled) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UIElementsUtility.cs:244)
UnityEngine.UIElements.UIEventRegistration.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UIElementsUtility.cs:79)
UnityEngine.UIElements.UIEventRegistration+<>c.<.cctor>b__1_2 (System.Int32 i, System.IntPtr ptr) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UIElementsUtility.cs:33)
UnityEngine.GUIUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr, System.Boolean& result) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:224)

{code}