BUG #18451: NULL fails to coerce to string when performing string comparison

The following bug has been logged on the website:

Bug reference:      18451
Logged by:          Darryl Dixon
Email address:      darryl.dixon@gmail.com
PostgreSQL version: 14.11
Operating system:   Ubuntu 22.04 64Bit
Description:

postdb=# select where 'ab' like '%a%';
--
(1 row)

postdb=# select where 'ab'||NULL like '%a%';
--
(0 rows)

postdb=# select where 'ab'||NULL::text like '%a%';
--
(0 rows)

postdb=# select where 'ab'||format('%s', NULL::text) like '%a%';
--
(1 row)

postdb=# select version();
                                                                version
                                                           

----------------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 14.11 (Ubuntu 14.11-0ubuntu0.22.04.1) on x86_64-pc-linux-gnu,
compiled by gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0, 64-bit
(1 row)