When you select a tile to paint with from the Tile Palette window, the following warning will be displayed in the Console:

Invalid texture used for cursor - check importer settings
UnityEditor.GridPaintPaletteWindow:OnEditModeStart(IToolModeOwner, SceneViewEditMode)
UnityEditorInternal.EditMode:ChangeEditMode(SceneViewEditMode, Bounds, IToolModeOwner) (at C:/buildslave/unity/build/Editor/Mono/Inspector/EditMode.cs:294)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

1. Install Unity
2. Open the attached project
3. Open the Tile Palette Window
4. Select the "Tiles" palette
5. Select a tile to paint with

Result:
Warning appears in the Console.

Expected Result:
No warnings should appear in the Console.