[ElmSharp] Fix SetNextFocusObject issue (#404)

To allow null on next parameter

diff --git a/src/ElmSharp/ElmSharp/Widget.cs b/src/ElmSharp/ElmSharp/Widget.cs
index 7b109fe..fd87e17 100644 (file)
--- a/src/ElmSharp/ElmSharp/Widget.cs
+++ b/src/ElmSharp/ElmSharp/Widget.cs
@@ -328,7 +328,7 @@ namespace ElmSharp
         /// <since_tizen> preview </since_tizen>
         public void SetNextFocusObject(EvasObject next, FocusDirection direction)
         {
-            Interop.Elementary.elm_object_focus_next_object_set(RealHandle, next.RealHandle, (int)direction);
+            Interop.Elementary.elm_object_focus_next_object_set(RealHandle, next?.RealHandle ?? IntPtr.Zero, (int)direction);
         }
 
         /// <summary>