[2D] NullReferenceException when trying to Edit in the Tile Palette Window when there is no Tile Palette

Steps to Repro:

1. create a new Project
2. open the Tile Palette Window
3. click on the Edit button

Result: NullReferenceExcpetion is given (see below for full error message)
Expected: Edit button should do nothing or should give a more user friendly message (e.g. You need to create a Tile Palette before you can Edit)

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.GridPaintPaletteClipboard.set_unlocked (Boolean value) (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteClipboard.cs:153)
UnityEditor.GridPaintPaletteWindow.DoClipboardHeader () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteWindow.cs:735)
UnityEditor.GridPaintPaletteWindow.OnGUI () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteWindow.cs:225)
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)