How to reproduce:
1. Open the attached project
2. Go to "ZooOverview" scene
3. Select "Terrain" object -> Inspector -> "Paint Terrain" -> "Paint Texture"
4. In the "Layers" -> "Layer Palette" section try to select the last or one of the last layers

Expected result: The texture is selected
Actual result: Another texture gets selected or Inspector closes and the "ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection." Error message appears

Tested on macOS

2022.1.0a4

Terrain Tools 4.0.3

Error message:
ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
System.Collections.Generic.List`1[T].get_Item (System.Int32 index) (at <4a132ca6e2db43bdb975b154d6271b43>:0)
UnityEditorInternal.ReorderableList.GetElementHeight (System.Int32 index) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:677)
UnityEditorInternal.ReorderableList.GetClampedDragPosition (UnityEngine.Rect listRect) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:1362)
UnityEditorInternal.ReorderableList.CalculateRowIndex (UnityEngine.Rect listRect) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:1367)
UnityEditorInternal.ReorderableList.DoDraggingAndSelection (UnityEngine.Rect listRect) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:1229)
UnityEditorInternal.ReorderableList.DoListElements (UnityEngine.Rect listRect, UnityEngine.Rect visibleRect) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:966)
UnityEditorInternal.ReorderableList.DoLayoutList () (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:718)
UnityEditor.TerrainTools.PaintTextureTool.LayersGUI (UnityEngine.Terrain terrain, UnityEditor.TerrainTools.IOnInspectorGUI editContext) (at Library/PackageCache/com.unity.terrain-tools@4.0.3/Editor/TerrainTools/PaintTextureTool.cs:458)
UnityEditor.TerrainTools.PaintTextureTool.OnInspectorGUI (UnityEngine.Terrain terrain, UnityEditor.TerrainTools.IOnInspectorGUI editContext) (at Library/PackageCache/com.unity.terrain-tools@4.0.3/Editor/TerrainTools/PaintTextureTool.cs:341)
UnityEditor.TerrainInspector.ShowPaint () (at /Users/bokken/buildslave/unity/build/Modules/TerrainEditor/TerrainInspector.cs:1529)
UnityEditor.TerrainInspector.OnInspectorGUI () (at /Users/bokken/buildslave/unity/build/Modules/TerrainEditor/TerrainInspector.cs:2050)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass62_0.<CreateIMGUIInspectorFromEditor>b__0 () (at /Users/bokken/buildslave/unity/build/ModuleOverrides/com.unity.ui/Editor/Inspector/InspectorElement.cs:645)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/bokken/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:189)