Steps to reproduce:

1. Open the attached project
2. Open the Test UI Document
3. Add a Button
4. Add a VisualElement
5. Add a Label nested inside VisualElement
6. Undo Label Creation
7. Undo VisualElement Creation
8. Redo VisualElement Creation
9. Redo Label Creation

Actual results: "Invalid UXML or USS: System.IndexOutOfRangeException: Index was outside the bounds of the array" error is thrown. The opened document becomes corrupted, preventing any changes

Expected results: Performing Undo/Redo operations does not result in thrown errors or data loss

Reproducible with versions: 2022.3.63f1, 6000.0.51f1, 6000.1.7f1, 6000.2.0b5

Tested on (OS): macOS 15.5

Notes:

• If the Test UI Document is reopened after the reproduction steps, it can be seen that any unsaved changes before the issue occurs are lost - Button from Step 3 is missing