[gtk/wip/chergert/action-critical-fixes: 2/2] actionmuxer: check for observer before unregistering

[Christian Hergert <chergert src gnome org>]

commit 0382e3b46c1e68b8daf61baa3873fc1d50c56192
Author: Christian Hergert <chergert redhat com>
Date:   Mon May 2 15:33:34 2022 -0700

    actionmuxer: check for observer before unregistering
    
    This can happen if the group can be resolved even when doing the initial
    registration of an action as observer will not yet be in the GSList of
    watchers (and therefore has no weak references).
    
    Fixes a warning like the following:
    
     g_object_weak_unref: couldn't find weak ref

 gtk/gtkactionmuxer.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkactionmuxer.c b/gtk/gtkactionmuxer.c
index 60ee06dc58..94f734ca91 100644
--- a/gtk/gtkactionmuxer.c
+++ b/gtk/gtkactionmuxer.c
@@ -991,13 +991,15 @@ gtk_action_muxer_unregister_observer (GtkActionObservable *observable,
                                       GtkActionObserver   *observer)
 {
   GtkActionMuxer *muxer = GTK_ACTION_MUXER (observable);
-  Action *action;
+  Action *action = find_observers (muxer, name);
 
-  action = find_observers (muxer, name);
   if (action)
     {
-      g_object_weak_unref (G_OBJECT (observer), gtk_action_muxer_weak_notify, action);
-      gtk_action_muxer_unregister_internal (action, observer);
+      if (g_slist_find (action->watchers, observer) != NULL)
+        {
+          g_object_weak_unref (G_OBJECT (observer), gtk_action_muxer_weak_notify, action);
+          gtk_action_muxer_unregister_internal (action, observer);
+        }
     }
 }