HPCC-12628 Fix internal error on ROW(record) with no defaults.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6675 from ghalliday/issue12628

HPCC-12628 Fix internal error on ROW(record) with no defaults.

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>