Hi Haibo,
Thanks for reviewing.
I agree that the SQL-callable pg_catalog.interval(interval, int4) path is the
important case to cover here. The v1 test was already exercising that direct
call, but it used a DO block intentionally so that the regression test checks
the SQLSTATE is invalid_parameter_value, rather than only matching the error
message text.
In v2, I kept that structure and updated the test comment to make this clearer.
Regards,
Feng