pub fn set_async_error_handler(
		&self,
		fun: impl (Fn(SyncIoError) -> Box<dyn Future<Output = ()> + Send + Sync>)
			+ Send
			+ Sync
			+ 'static,
	) -> Ticket {
		self.control(Control::SetAsyncErrorHandler(Arc::new(fun)))
	}
Set the error handler (async version).
crates/supervisor/src/job/job.rs