[gnome-chess] scene: properly disconnect game signals

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 400a556af531b3e2606ecd87fe8505603c010e62
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Fri Dec 25 10:06:49 2020 -0600

    scene: properly disconnect game signals

 src/chess-scene.vala | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)
---
diff --git a/src/chess-scene.vala b/src/chess-scene.vala
index 021384c..fde2a26 100644
--- a/src/chess-scene.vala
+++ b/src/chess-scene.vala
@@ -100,14 +100,26 @@ public class ChessScene : Object
                 animate_timeout_id = 0;
                 animating = false;
             }
+
+            if (_game != null)
+            {
+                _game.moved.disconnect (moved_cb);
+                _game.paused.disconnect (paused_cb);
+                _game.unpaused.disconnect (unpaused_cb);
+                _game.undo.disconnect (undo_cb);
+            }
+
             _game = value;
-            _move_number = -1;
-            selected_rank = -1;
-            selected_file = -1;
+
             _game.moved.connect (moved_cb);
             _game.paused.connect (paused_cb);
             _game.unpaused.connect (unpaused_cb);
             _game.undo.connect (undo_cb);
+
+            _move_number = -1;
+            selected_rank = -1;
+            selected_file = -1;
+
             update_board ();
         }
     }