Sql. Subqueries with invalid aggregates in subqueries are not rejected

# this will fail, because "i" is not an aggregate but the SUM(i1.i) turns this query into an aggregate
skipif ignite3
statement error
SELECT i, (SELECT SUM(i1.i)) FROM integers i1;

# PG: ERROR:  column "i1.i" must appear in the GROUP BY clause or be used in an aggregate function
skipif ignite3
statement error
SELECT i+1, (SELECT SUM(i1.i)) FROM integers i1;