Cleaning up after block dismount

[Lovor01]

I would like to do some actions when block is deleted from editor. I currently use this code:

	// cleanup of meta data from post, note that return value is cleanup function
	useEffect(() => () => {
			setMeta({ ...meta, term_definition: terms.filter(el => el.ID !== attributes.ID) });
			deleteEntityRecord('extra_table/v1', 'events_meta', events_meta_ID);
		}
	, []);

However, it seems that sometimes block variables (attributes and state - events_meta_ID is local state to block) are asynchronously deleted before this code is run and therefore this code fails. Is there proper way to do this - with one exception: I would not like to use class components instead of functions for block definition. So please, no componentWillUnmount() solutions?