[chronojump] Fixed some possible crash on deleting encoder sets

[Xavier de Blas <xaviblas src gnome org>]

commit 09d1002f0c175c269bd6e9ab5e4bb6f5f2658953
Author: Xavier de Blas <xaviblas gmail com>
Date:   Mon Dec 11 15:38:48 2017 +0100

    Fixed some possible crash on deleting encoder sets

 src/gui/encoder.cs |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/src/gui/encoder.cs b/src/gui/encoder.cs
index f6e2778..c1d9e5b 100644
--- a/src/gui/encoder.cs
+++ b/src/gui/encoder.cs
@@ -1806,7 +1806,7 @@ public partial class ChronoJumpWindow
                //find related curves using encoderSignalCurve table
                ArrayList linkedCurves = SqliteEncoder.SelectSignalCurve(
                                false, signalID, -1, -1, -1);   //DBopened, signal, curve, msStart, msEnd
-               
+
                //delete related curves: files and records from encoder table
                foreach(EncoderSignalCurve esc in linkedCurves) 
                {
@@ -1814,14 +1814,15 @@ public partial class ChronoJumpWindow
                        EncoderSQL eSQL = (EncoderSQL) SqliteEncoder.Select(
                                        false, esc.curveID, -1, -1, Constants.EncoderGI.ALL,
                                        -1, "curve", EncoderSQL.Eccons.ALL, false, true)[0];
-                       
+
                        //delete file
-                       Util.FileDelete(eSQL.GetFullURL(false));        //don't convertPathToR
+                       if(eSQL != null)
+                               Util.FileDelete(eSQL.GetFullURL(false));        //don't convertPathToR
 
                        //delete curve from encoder table
                        Sqlite.Delete(false, Constants.EncoderTable, esc.curveID);
                }
-               
+
                //delete related records from encoderSignalCurve table
                Sqlite.DeleteSelectingField(false, Constants.EncoderSignalCurveTable, 
                                "signalID", signalID.ToString());
@@ -1829,7 +1830,7 @@ public partial class ChronoJumpWindow
                //delete related triggers
                SqliteTrigger.DeleteByModeID(false, signalID);
        }
-       
+
        void on_button_encoder_export_all_curves_clicked (object o, EventArgs args) 
        {
                checkFile(Constants.CheckFileOp.ENCODER_CAPTURE_EXPORT_ALL);