From 702e8392944d7fde9ce17856b44be31c5fc111b9 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Sun, 24 Jul 2022 16:13:33 +0200
Subject: [PATCH] Don't throw trying to unsub if not subscribed.

This can happen when re-evaluating the value store if a style is detached before its frame is evaluated.
---
 src/Avalonia.Base/Styling/Activators/StyleActivatorBase.cs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Avalonia.Base/Styling/Activators/StyleActivatorBase.cs b/src/Avalonia.Base/Styling/Activators/StyleActivatorBase.cs
index a4639b8feb..412151b92f 100644
--- a/src/Avalonia.Base/Styling/Activators/StyleActivatorBase.cs
+++ b/src/Avalonia.Base/Styling/Activators/StyleActivatorBase.cs
@@ -29,6 +29,9 @@ namespace Avalonia.Styling.Activators
 
         public void Unsubscribe(IStyleActivatorSink sink)
         {
+            if (_sink is null)
+                return;
+
             if (_sink != sink)
             {
                 throw new AvaloniaInternalException("StyleActivatorSink is not subscribed.");