Crash with LEAD function in ColumnStore with 'char' field type

use test;

create table ct1 (a int, b char) engine=columnstore;

insert into ct1 values (1, 'a'), (2, 'b'), (3, NULL);

select lead(a) over (order by a) from ct1;  -- Correct result

select lead(b, 1, 'T') over (order by a) from ct1;  -- Correct result

select lead(b) over (order by a) from ct1;  -- Crash happens here

select lead(b, 1, NULL) over (order by a) from ct1;  -- This also crashes

MariaDB [test]> select lead(b, 1, NULL) over (order by a) from ct1;

ERROR 1815 (HY000): Internal error: InetStreamSocket::readToMagic: Remote is closed

MariaDB [test]> select lead(b, 3, NULL) over (order by a) from ct1;

ERROR 1815 (HY000): Internal error: InetStreamSocket::readToMagic: Remote is closed