Eng 6012 inexists sp

HSQL is having trouble parsing subqueries with the user params. It throwing NullPointerException. 
    select r2.a from r2 where exists ( SELECT 1 from R2 WHERE r2.c = ?);

The other example where HSQL fails is a subquery with more than one parent TVE - ArrayOutOfBoundException:
select r2.c from r2 where  exists  (select 1 from r3 where r3.a = r2.c and r3.a = r2.d)

I already have both examples under the testHSQLFailed test case

The test case with parent TVE  already there. I added one more with parent and grand-parent TVEs (one param per subquery though)