private bool ShouldHandle(PersistentEvent ev) {
     return ev.IsError() && ev.Data.ContainsKey(Event.KnownDataKeys.SimpleError);
 }
        public override string GetStackTitle(PersistentEvent ev)
        {
            if (String.IsNullOrWhiteSpace(ev.Message) && ev.IsError())
                return "Unknown Error";

            return ev.Message ?? ev.Source ?? $"{ev.Type} Event".TrimStart();
        }