[chronojump] TriggerList cannot be null or empty

[Xavier de Blas <xaviblas src gnome org>]

commit 7c4e08d9f7c3d9892c64535ea07964c82ed40a8c
Author: Xavier de Blas <xaviblas gmail com>
Date:   Wed Apr 18 23:33:24 2018 +0200

    TriggerList cannot be null or empty

 src/encoder.cs |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/encoder.cs b/src/encoder.cs
index 7a5c196..abd204e 100644
--- a/src/encoder.cs
+++ b/src/encoder.cs
@@ -184,6 +184,10 @@ public class EncoderGraphROptions
                this.crossValidate = crossValidate;
                this.cutByTriggers = cutByTriggers;
                this.triggerList = triggerList;
+
+               //ensure triggerList is not null or blank
+               if(triggerList == null || triggerList == "")
+                       triggerList = "-1";
        }
 
        public override string ToString() {