From 3925d92d5c12c393ab7e2a8054c01b56981c7b60 Mon Sep 17 00:00:00 2001
From: lindexi <lindexi_gd@163.com>
Date: Mon, 30 May 2022 11:49:49 +0800
Subject: [PATCH] Return null when the PrefetchedValue is the UnsetValue.

---
 .../System/Windows/Markup/BamlRecordReader.cs          | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/BamlRecordReader.cs b/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/BamlRecordReader.cs
index 46d99d545a4..85b021dd3d5 100644
--- a/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/BamlRecordReader.cs
+++ b/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/BamlRecordReader.cs
@@ -5680,7 +5680,15 @@ internal StaticResourceHolder(object resourceKey, DeferredResourceReference pref
 
         internal override DeferredResourceReference PrefetchedValue
         {
-            get { return _prefetchedValue; }
+            get
+            {
+                if (_prefetchedValue == null || _prefetchedValue.Value == DependencyProperty.UnsetValue)
+                {
+                    return null;
+                }
+
+                return _prefetchedValue;
+            }
         }
 
         #endregion Methods