How to reproduce:
1. Download and open the attached project
2. In the Project window, select both prefabs
3. In the Inspector window, press "Select half"
Expected outcome: One prefab is selected
Actual outcome: "NullReferenceException" and "IndexOutOfRangeException" errors appear in the console window
Reproducible with: 2020.3.42f1, 2021.3.15f1, 2022.1.24f1, 2022.2.1f1, 2023.1.0a21