From dcbd54f103037605c9a1191933e8e0e9d92cba45 Mon Sep 17 00:00:00 2001
From: Joseph Humfrey <joseph.humfrey@inklestudios.com>
Date: Wed, 28 Jun 2017 11:05:06 +0100
Subject: [PATCH] Fix for attempting to copy a null callstack

---
 ink-engine-runtime/StoryState.cs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ink-engine-runtime/StoryState.cs b/ink-engine-runtime/StoryState.cs
index 7a08447c..8e3dc622 100755
--- a/ink-engine-runtime/StoryState.cs
+++ b/ink-engine-runtime/StoryState.cs
@@ -256,7 +256,8 @@ internal StoryState Copy()
             }
 
             copy.callStack = new CallStack (callStack);
-            copy._originalCallstack = new CallStack(_originalCallstack);
+            if( _originalCallstack != null )
+                copy._originalCallstack = new CallStack(_originalCallstack);
 
             copy.variablesState = new VariablesState (copy.callStack, story.listDefinitions);
             copy.variablesState.CopyFrom (variablesState);