From ab1336055d6de4e19168b56ca90c141f7a02a3be Mon Sep 17 00:00:00 2001
From: Kenneth Skovhede <kenneth@hexad.dk>
Date: Fri, 14 Oct 2016 00:50:06 +0200
Subject: [PATCH] Added a guard to prevent AnalyzeFilter from crashing if it is
 called with a null input

---
 Duplicati/Library/Utility/FilterExpression.cs | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/Duplicati/Library/Utility/FilterExpression.cs b/Duplicati/Library/Utility/FilterExpression.cs
index 07789fe65..237d34baf 100644
--- a/Duplicati/Library/Utility/FilterExpression.cs
+++ b/Duplicati/Library/Utility/FilterExpression.cs
@@ -382,12 +382,13 @@ namespace Duplicati.Library.Utility
             Tuple<bool, bool> cacheLookup;
 
             // Check for cached results
-            lock(_matchLock)
-                if (_matchFallbackLookup.TryGetValue(filter, out cacheLookup))
-                {
-                    includes = cacheLookup.Item1;
-                    excludes = cacheLookup.Item2;
-                }
+            if (filter != null)
+                lock(_matchLock)
+                    if (_matchFallbackLookup.TryGetValue(filter, out cacheLookup))
+                    {
+                        includes = cacheLookup.Item1;
+                        excludes = cacheLookup.Item2;
+                    }
 
             // Figure out what components are in the filter
             if (cacheLookup == null)