From 8a35356e847eb21ed49b9b0ec1d0f687fe20f9e5 Mon Sep 17 00:00:00 2001
From: Thomas Ibel <tibel@users.noreply.github.com>
Date: Sun, 1 Jun 2014 12:04:42 +0200
Subject: [PATCH] check that AssociatedObject is set before Execute() is called

---
 src/Caliburn.Xaml.Universal/Behaviors/TriggerAction.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Caliburn.Xaml.Universal/Behaviors/TriggerAction.cs b/src/Caliburn.Xaml.Universal/Behaviors/TriggerAction.cs
index a28bd23..d82f81d 100644
--- a/src/Caliburn.Xaml.Universal/Behaviors/TriggerAction.cs
+++ b/src/Caliburn.Xaml.Universal/Behaviors/TriggerAction.cs
@@ -1,4 +1,5 @@
-using Microsoft.Xaml.Interactivity;
+using System;
+using Microsoft.Xaml.Interactivity;
 using Windows.UI.Xaml;
 
 namespace Caliburn.Light
@@ -57,6 +58,9 @@ protected virtual void OnDetaching() { }
         /// </returns>
         public object Execute(object sender, object parameter)
         {
+            if (AssociatedObject == null)
+                throw new InvalidOperationException("AssociatedObject was not set before Execute.");
+
             Invoke(parameter);
             return null;
         }