[libchamplain] Fix a warning when attempting to remove an actor that has been destroyed

[Pierre-Luc Beaudoin <plbeaudoin src gnome org>]

commit 30e9f1364077d5b144f444c53dd298ae4d3ffe94
Author: Pierre-Luc Beaudoin <pierre-luc pierlux com>
Date:   Thu Sep 10 13:03:59 2009 -0400

    Fix a warning when attempting to remove an actor that has been destroyed

 champlain/champlain-view.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/champlain/champlain-view.c b/champlain/champlain-view.c
index a7e4e0a..ffb4b6a 100644
--- a/champlain/champlain-view.c
+++ b/champlain/champlain-view.c
@@ -1764,7 +1764,8 @@ view_load_visible_tiles (ChamplainView *view)
           {
             actor = champlain_tile_get_actor (tile);
             group = champlain_zoom_level_get_actor (level);
-            clutter_container_remove_actor (CLUTTER_CONTAINER (group), actor);
+            if (actor != NULL)
+              clutter_container_remove_actor (CLUTTER_CONTAINER (group), actor);
           }
         champlain_zoom_level_remove_tile (level, tile);
         count = champlain_zoom_level_tile_count (level);