fix(timer): fix working with nested lv_async_calls

fixes: #3940

src/core/lv_obj_tree.c

@@ -390,6 +390,12 @@ static void obj_del_core(lv_obj_t * obj)
         indev = lv_indev_get_next(indev);
     }
 
+    /*Delete all pending async del-s*/
+    lv_res_t async_cancel_res = LV_RES_OK;
+    while(async_cancel_res == LV_RES_OK) {
+        async_cancel_res = lv_async_call_cancel(lv_obj_del_async_cb, obj);
+    }
+
     /*All children deleted. Now clean up the object specific data*/
     _lv_obj_destruct(obj);
 

src/misc/lv_async.c

@@ -98,8 +98,11 @@ lv_res_t lv_async_call_cancel(lv_async_cb_t async_xcb, void * user_data)
 
 static void lv_async_timer_cb(lv_timer_t * timer)
 {
+    /*Save the info because an lv_async_call_cancel might delete it in the callback*/
     lv_async_info_t * info = (lv_async_info_t *)timer->user_data;
-
+    lv_async_info_t info_save = *info;
-    info->cb(info->user_data);
+    lv_timer_del(timer);
     lv_free(info);
+
+    info_save.cb(info_save.user_data);
 }