From 9d67fc6a613ac1322621b0b9a281eb4ce3194eac Mon Sep 17 00:00:00 2001
From: menno <menno@DESKTOP-6SF2R34>
Date: Tue, 25 Jun 2019 13:41:59 +0200
Subject: [PATCH] fix null reference

---
 source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs b/source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs
index 636c954b..188081b1 100644
--- a/source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs
+++ b/source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs
@@ -869,7 +869,7 @@ internal void CloseInternal()
           PreviousContainerId = (parentAsGroup as ILayoutPaneSerializable).Id;
           
           // This parentAsGroup will be removed in the GarbageCollection below
-          if (parentAsGroup.Children.Count() == 1 && parentAsGroup.Parent != null)
+          if (parentAsGroup.Children.Count() == 1 && parentAsGroup.Parent != null && Root.Manager != null)
           {
             Parent = Root.Manager.Layout;
             PreviousContainer = parentAsGroup.Parent;