From ab30fd343b04382a34bc2e4e70b199f36df2792d Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Wed, 14 Jun 2017 02:00:12 +0200
Subject: [PATCH] Handle no previous measure/arrange.

This shouldn't happen, but if it does, don't crash.
---
 src/Avalonia.Layout/LayoutManager.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Layout/LayoutManager.cs b/src/Avalonia.Layout/LayoutManager.cs
index f1f0749d41..73aadcd545 100644
--- a/src/Avalonia.Layout/LayoutManager.cs
+++ b/src/Avalonia.Layout/LayoutManager.cs
@@ -165,7 +165,7 @@ namespace Avalonia.Layout
                 {
                     root.Measure(Size.Infinity);
                 }
-                else
+                else if (control.PreviousMeasure.HasValue)
                 {
                     control.Measure(control.PreviousMeasure.Value);
                 }
@@ -185,7 +185,7 @@ namespace Avalonia.Layout
                 {
                     root.Arrange(new Rect(control.DesiredSize));
                 }
-                else
+                else if (control.PreviousArrange.HasValue)
                 {
                     control.Arrange(control.PreviousArrange.Value);
                 }