Group By results in RuntimeException[BUG]

[ghost]

Describe the bug
Group By results in RuntimeException.

Or for query issues:

1. Run the query '
   select str1, date0, C1, case when not C1 is null then C1 else {ts '1899-12-28 00:00:00'} end as C2, case when C1 is null then 0 else 1 end as C3 from (select str1, date0, date0 as C1 from calcs ) as ITBL group by str1, date0, C1
   '
2. See error RuntimeException

Expected behavior
Return valid results without an exception.

Additional context
The query works as expected without group by.