[longomatch] Fix exception when event time is null

[Andoni Morales Alastruey <amorales src gnome org>]

commit 5fc5e10ed191244fea0cb05a26f4d4f010fc2a3b
Author: Andoni Morales Alastruey <ylatuya gmail com>
Date:   Mon Sep 8 18:56:50 2014 +0200

    Fix exception when event time is null

 LongoMatch.Core/Store/TimeNode.cs |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/LongoMatch.Core/Store/TimeNode.cs b/LongoMatch.Core/Store/TimeNode.cs
index 2fbfabc..759dae0 100644
--- a/LongoMatch.Core/Store/TimeNode.cs
+++ b/LongoMatch.Core/Store/TimeNode.cs
@@ -59,7 +59,7 @@ namespace LongoMatch.Core.Store
                        }
                        set {
                                start = value;
-                               if (start > eventTime) {
+                               if (eventTime != null && start > eventTime) {
                                        eventTime = start;
                                }
                        }
@@ -74,7 +74,7 @@ namespace LongoMatch.Core.Store
                        }
                        set {
                                stop = value;
-                               if (stop < eventTime) {
+                               if (eventTime != null && stop < eventTime) {
                                        eventTime = stop;
                                }
                        }