Extensions: do not wait on widget if dialog is deleted

If the dialog is about to be deleted, it's too late to care about
the widget (it has already been removed from the UI).

modules/misc/lua/libs/dialog.c

@@ -862,8 +862,12 @@ static int vlclua_dialog_delete_widget( lua_State *L )
 
     vlc_mutex_lock( &p_dlg->lock );
 
-    /* Same remarks as for dialog delete */
-    while( p_widget->p_sys_intf != NULL )
+    /* Same remarks as for dialog delete.
+     * If the dialog is deleted or about to be deleted, then there is no
+     * need to wait on this particular widget that already doesn't exist
+     * anymore in the UI */
+    while( p_widget->p_sys_intf != NULL && !p_dlg->b_kill
+           && p_dlg->p_sys_intf != NULL )
     {
         vlc_cond_wait( &p_dlg->cond, &p_dlg->lock );
     }