From 6d79b4485080ed017cb5b2fc98b34e1bb38c4a14 Mon Sep 17 00:00:00 2001
From: Lars Brubaker <larsbrubaker@gmail.com>
Date: Wed, 25 May 2022 15:13:27 -0700
Subject: [PATCH] Make sure we validate there is an undo buffer before we use
 it

---
 .../ApplicationView/Config/PrinterConfig.cs            | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/MatterControlLib/ApplicationView/Config/PrinterConfig.cs b/MatterControlLib/ApplicationView/Config/PrinterConfig.cs
index 3472dcfe3..a12aa3f14 100644
--- a/MatterControlLib/ApplicationView/Config/PrinterConfig.cs
+++ b/MatterControlLib/ApplicationView/Config/PrinterConfig.cs
@@ -79,8 +79,11 @@ namespace MatterHackers.MatterControl
 			var scene = Bed?.Scene;
 			if (scene != null)
 			{
+                var undoBuffer = scene.UndoBuffer;
+
                 if (sceneOverrides != null
-                    && undoBufferHashCode == scene.UndoBuffer.GetLongHashCode())
+                    && undoBuffer != null
+                    && undoBufferHashCode == undoBuffer.GetLongHashCode())
                 {
 					return sceneOverrides;
                 }
@@ -162,7 +165,10 @@ namespace MatterHackers.MatterControl
 				}
 
 				// return the current set
-				undoBufferHashCode = scene.UndoBuffer.GetLongHashCode();
+				if (undoBuffer != null)
+				{
+					undoBufferHashCode = undoBuffer.GetLongHashCode();
+				}
 				return sceneOverrides;
 			}