BUG #19418: SQL/JSON JSON_VALUE() does not conform to ISO/IEC 9075-2:2023(E) 6.34

The following bug has been logged on the website:

Bug reference:      19418
Logged by:          Lukas Eder
Email address:      lukas.eder@gmail.com
PostgreSQL version: 18.2
Operating system:   Linux
Description:

When using the ISO/IEC 9075-2:2023(E) 6.34 <JSON value constructor by query>
syntax, 6.34 GR 4) b) i) says that empty tables should produce a JSON array
with no elements (intuitively), not NULL.

Try this:

  select json_array(select 1 where false);

It produces NULL, not []