BUG #18111: Query hangs when trying to INSERT empty string into NOT NULL table

The following bug has been logged on the website:

Bug reference:      18111
Logged by:          Maciej Klimkowicz
Email address:      maciej.klimkowicz@oxla.com
PostgreSQL version: 15.1
Operating system:   Ubuntu
Description:

Steps to reproduce:

1.CREATE TABLE texttable (col1 TEXT NOT NULL);
2.INSERT INTO texttable (col1) VALUES ('');

Query hangs indefinitely.
For NULL column it works as expected.