[gnome-builder] layout: add extra destruction protection

[Christian Hergert <chergert src gnome org>]

commit 682ad8e561f8c4fa3c9525f59f244448685d84a9
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jun 14 01:05:13 2018 -0700

    layout: add extra destruction protection

 src/libide/layout/ide-layout-stack.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/src/libide/layout/ide-layout-stack.c b/src/libide/layout/ide-layout-stack.c
index 18eb3659b..353ab2ed4 100644
--- a/src/libide/layout/ide-layout-stack.c
+++ b/src/libide/layout/ide-layout-stack.c
@@ -209,7 +209,11 @@ ide_layout_stack_notify_visible_child (IdeLayoutStack *self,
   if (gtk_widget_in_destruction (GTK_WIDGET (self)))
     return;
 
-  visible_child = gtk_stack_get_visible_child (priv->stack);
+  if ((visible_child = gtk_stack_get_visible_child (priv->stack)))
+    {
+      if (gtk_widget_in_destruction (visible_child))
+        visible_child = NULL;
+    }
 
   /*
    * Mux/Proxy actions to our level so that they also be activated