[chronojump] Fixed a crash on CairoBars encoder since recent commits

[Xavier de Blas <xaviblas src gnome org>]

commit dd0d73b8d361aaa072658087788acb177d8aa2ab
Author: Xavier de Blas <xaviblas gmail com>
Date:   Fri Apr 8 19:40:18 2022 +0200

    Fixed a crash on CairoBars encoder since recent commits

 src/gui/eventExecute.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gui/eventExecute.cs b/src/gui/eventExecute.cs
index 26ed8cb04..19cf2d784 100644
--- a/src/gui/eventExecute.cs
+++ b/src/gui/eventExecute.cs
@@ -3948,7 +3948,7 @@ public class CairoPaintBarplotPreEncoder : CairoPaintBarsPre
                if(lineData_l.Count > 0)
                        cb.LineData_l = lineData_l; //range
 
-               if(eccOverload_l.Count > 0)
+               if(eccOverload_l != null && eccOverload_l.Count > 0)
                {
                        cb.EccOverload_l = eccOverload_l;
                        if (preferences.encoderCaptureInertialEccOverloadMode ==