Changing TintBrush.cs m_Color to another color causes NullReferenceException

[Demkeys]

I opened up the TintBrush.cs file and changed the value of m_Color from Color.white to Color.blue. That's it. I hit save and go back to the Editor. Suddenly I get a NullReferenceException saying the following:
NullReferenceException: Object reference not set to an instance of an object

UnityEditor.GridPaintingState.UnregisterPainterInterest (UnityEngine.Object painter) (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintingState.cs:197)
UnityEditor.GridPaintPaletteWindow.OnDisable () (at C:/buildslave/unity/build/Modules/TilemapEditor/Editor/Managed/Grid/GridPaintPaletteWindow.cs:565)

Anyone else having this issue?
I should mention that I'm using Unity 2017.3.

[Demkeys]

UPDATE: I installed the Unity 2017.3.0p4 Patch and that solved the issue. The error isn't popping up anymore.