From 5873057817f5b2dd76d6b1f4f3e00c524d4ecb78 Mon Sep 17 00:00:00 2001
From: Dariusz Komosinski <darek.komosinski@gmail.com>
Date: Sun, 26 Jan 2020 20:53:11 +0100
Subject: [PATCH] Add sanity check.

---
 src/Avalonia.Styling/Styling/Selector.cs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Avalonia.Styling/Styling/Selector.cs b/src/Avalonia.Styling/Styling/Selector.cs
index b8a67e6d96..52c6ae4027 100644
--- a/src/Avalonia.Styling/Styling/Selector.cs
+++ b/src/Avalonia.Styling/Styling/Selector.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 
 namespace Avalonia.Styling
 {
@@ -68,6 +69,8 @@ namespace Avalonia.Styling
                 }
                 else if (match.Result == SelectorMatchResult.Sometimes)
                 {
+                    Debug.Assert(match.Activator != null);
+
                     if (inputs != null)
                     {
                         inputs.Add(match.Activator);