[chronojump] Fixed crash if force sensor load an empty file

[Xavier de Blas <xaviblas src gnome org>]

commit c7fbf419bca0bb11c0d49be46f3516e8a7d38cd6
Author: Xavier de Blas <xaviblas gmail com>
Date:   Fri Jun 15 11:38:45 2018 +0200

    Fixed crash if force sensor load an empty file

 src/gui/forceSensorAnalyze.cs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/src/gui/forceSensorAnalyze.cs b/src/gui/forceSensorAnalyze.cs
index cfae70a0..11eea99f 100644
--- a/src/gui/forceSensorAnalyze.cs
+++ b/src/gui/forceSensorAnalyze.cs
@@ -684,6 +684,9 @@ public partial class ChronoJumpWindow
 
        private void forceSensorAnalyzeManualGraphDo(Rectangle allocation)
        {
+               if(fsAI.GetLength() == 0)
+                       return;
+
                LogB.Information("forceSensorAnalyzeManualGraphDo() START");
                bool debug = false;
 
@@ -883,7 +886,7 @@ public partial class ChronoJumpWindow
        bool forceSensorAIChanged = false;
        private void on_hscale_force_sensor_ai_a_value_changed (object o, EventArgs args)
        {
-               if(fsAI == null)
+               if(fsAI == null || fsAI.GetLength() == 0)
                        return;
 
                int count = Convert.ToInt32(hscale_force_sensor_ai_a.Value);
@@ -903,7 +906,7 @@ public partial class ChronoJumpWindow
        }
        private void on_hscale_force_sensor_ai_b_value_changed (object o, EventArgs args)
        {
-               if(fsAI == null)
+               if(fsAI == null || fsAI.GetLength() == 0)
                        return;
 
                int count = Convert.ToInt32(hscale_force_sensor_ai_b.Value);