*Steps to reproduce:*
1. Create new Unity project using Universal 2D Template
2. In Project window create Isometric Rule Tile (Create > 2D > Tiles > Isometric Rule Tile)
3. In Inspector > Tiling Rules list press “+” button
4. Then press “-“ button
5. Press “+” again
6. Observe Console window

*Actual results:* “ArgumentOutOfRangeException” error spammed when adding Tiling Rules

*Expected results:* No errors are spammed when adding Tiling Rules

*Reproducible with versions:* 6000.1.0b13 (81eefeb8a871), 6000.1.16f1, 6000.2.1f1, 6000.3.0a5

*Not reproducible with versions:* 6000.0.56f1, 6000.1.0b12 (8e2fce1fdf6e)

*Tested on (OS):* macOS Silicon, Sequoia 15.6 (M1)

*Error:*
{code:java}
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].set_Item (System.Int32 index, T value) (at <016d35b5449b460ca65d15b1a0aee10a>:0)
UnityEditor.RuleTileEditor.OnAddElement (System.Object obj) (at ./Library/PackageCache/com.unity.2d.tilemap.extras@eefc9f6533f8/Editor/Tiles/RuleTile/RuleTileEditor.cs:374)
UnityEditor.RuleTileEditor.OnAddDropdownElement (UnityEngine.Rect rect, UnityEditorInternal.ReorderableList list) (at ./Library/PackageCache/com.unity.2d.tilemap.extras@eefc9f6533f8/Editor/Tiles/RuleTile/RuleTileEditor.cs:410)
UnityEditorInternal.ReorderableList+Defaults.DrawFooter (UnityEngine.Rect rect, UnityEditorInternal.ReorderableList list) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/ReorderableList.cs:212)
UnityEditorInternal.ReorderableList.DoListFooter (UnityEngine.Rect footerRect) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/ReorderableList.cs:1100)
UnityEditorInternal.ReorderableList.DoLayoutList () (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/ReorderableList.cs:753)
UnityEditor.RuleTileEditor.OnInspectorGUI () (at ./Library/PackageCache/com.unity.2d.tilemap.extras@eefc9f6533f8/Editor/Tiles/RuleTile/RuleTileEditor.cs:532)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass79_0.<CreateInspectorElementUsingIMGUI>b__0 () (at /Users/bokken/build/output/unity/unity/Editor/Mono/UIElements/Inspector/InspectorElement.cs:747)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:219)
{code}