[longomatch] Fix exception closing the game unitis editor

[Andoni Morales Alastruey <amorales src gnome org>]

commit 37a293e8f92ac2e2e03e53edbcce3a5094411631
Author: Andoni Morales Alastruey <ylatuya gmail com>
Date:   Thu Aug 22 14:21:53 2013 +0200

    Fix exception closing the game unitis editor

 .../Gui/Component/CategoriesTemplateEditor.cs      |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/LongoMatch.GUI/Gui/Component/CategoriesTemplateEditor.cs 
b/LongoMatch.GUI/Gui/Component/CategoriesTemplateEditor.cs
index 26ab949..8beab52 100644
--- a/LongoMatch.GUI/Gui/Component/CategoriesTemplateEditor.cs
+++ b/LongoMatch.GUI/Gui/Component/CategoriesTemplateEditor.cs
@@ -235,6 +235,8 @@ namespace LongoMatch.Gui.Component
                        
                        desc = Catalog.GetString ("Game periods") + " (eg: 1 2 ex1 ex2) ";
                        res = MessagesHelpers.QueryMessage (this, desc, "", String.Join (" ", 
Template.GamePeriods));
+                       if (res == null)
+                               return;
                        
                        periods = new List<string> (res.Split(' '));
                        if (periods.Count == 0) {