Tilemap Palette asset can be dragged into Tilemap Palette Window. Dragging a Tilemap Palette asset into the window 3+ times will generate various errors. Repeated dragging can lead to the Editor locking up.

STEPS TO REPRO:

1. open the Tilemap Palette Window
2. create a new Tilemap in the hierarchy
3. create a new Tilemap Palette
4. drag the Palette asset into the Tile Palette Window

Result: The user is able to drag the Palette asset into the Palette Window. Doing so repeatedly (3+) can cause various errors (see below) and doing so excessively (15+) can cause the editor to lock up.

Expected: The user should not be able to drag the Palette asset into the Palette Window because it is not a Tile, Sprite, or Sprite Texture.

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Matrix stack full depth reached
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

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IndexOutOfRangeException: Array index is out of range.
UnityEditorInternal.GridEditorUtility.GenerateCachedGridMesh (UnityEngine.GridLayout gridLayout, Color color, Single screenPixelSize, RectInt bounds) (at C:/buildslave/unity/build/Editor/Mono/Grid/GridEditorUtility.cs:310)
UnityEditor.GridPaintPaletteClipboard.RenderGrid () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteClipboard.cs:578)
UnityEditor.GridPaintPaletteClipboard.Render () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteClipboard.cs:535)
UnityEditor.GridPaintPaletteClipboard.OnGUI () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteClipboard.cs:377)
UnityEditor.GridPaintPaletteWindow.OnClipboardGUI (Rect position) (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteWindow.cs:819)
UnityEditor.GridPaintPaletteWindow.OnGUI () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteWindow.cs:230)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:283)
UnityEditor.HostView.Invoke (System.String methodName) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:276)
UnityEditor.HostView.InvokeOnGUI (Rect onGUIPosition) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:243)
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Matrix stack full depth reached
UnityEngine.GL:PushMatrix()
UnityEditorInternal.GridEditorUtility:DrawGridGizmo(GridLayout, Transform, Color, Mesh&, Material&) (at C:/buildslave/unity/build/Editor/Mono/Grid/GridEditorUtility.cs:246)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)