Thank you for responding! Good points.
However, I don't see consistency between the results of these two statements: select jsonb_agg((select 1 where false)); select sum((select 1 where false)); Therefore another option I would like to suggest is returning the same null value-types for the sum() and json_agg(). So the select jsonb_agg((select 1 where false)); would return null as opposed to [null]. In this case it would be compatible with coalesce() --- Thanks Jordan Deitch
