[chronojump] Fixed a crash on load a forceSensor set when currentForceSensor == null (no person changed)

[Xavier de Blas <xaviblas src gnome org>]

commit 34e24cb1e0849d780069a86b1e61f2ef12d22f5f
Author: Xavier de Blas <xaviblas gmail com>
Date:   Mon Apr 25 16:43:59 2022 +0200

    Fixed a crash on load a forceSensor set when currentForceSensor == null (no person changed)

 src/gui/app1/forceSensor.cs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/gui/app1/forceSensor.cs b/src/gui/app1/forceSensor.cs
index c30beb086..5d16507b2 100644
--- a/src/gui/app1/forceSensor.cs
+++ b/src/gui/app1/forceSensor.cs
@@ -2218,7 +2218,8 @@ LogB.Information(" fs R ");
                genericWin.ShowEditRow(false);
 
                //select row corresponding to current signal
-               genericWin.SelectRowWithID(0, currentForceSensor.UniqueID); //colNum, id
+               if(currentForceSensor != null)
+                       genericWin.SelectRowWithID(0, currentForceSensor.UniqueID); //colNum, id
 
                genericWin.VideoColumn = 7;
                genericWin.CommentColumn = 8;