<?php
$x = NULL;
if (is_null($x)) { echo "x is null\n"; } else { echo "x is not null\n"; }
if (isset($x)) { echo "x is set\n"; } else { echo "x is not set\n"; }
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
x is null
x is not set