Online PHP editor | output for QRW3K

Output for 7.0.33, 7.1.25 - 7.1.31, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.4, 8.3.6: string(15) "example.org/wat" bool(false)
Output for 8.3.5: 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 string(15) "example.org/wat" bool(false)
Output for 5.6.38 - 5.6.40: Notice: Use of undefined constant FILTER_VALIDATE_DOMAIN - assumed 'FILTER_VALIDATE_DOMAIN' in /in/QRW3K on line 4 Warning: filter_var() expects parameter 2 to be long, string given in /in/QRW3K on line 4 Notice: Use of undefined constant FILTER_VALIDATE_DOMAIN - assumed 'FILTER_VALIDATE_DOMAIN' in /in/QRW3K on line 5 Notice: Use of undefined constant FILTER_FLAG_HOSTNAME - assumed 'FILTER_FLAG_HOSTNAME' in /in/QRW3K on line 5 Warning: filter_var() expects parameter 2 to be long, string given in /in/QRW3K on line 5 NULL NULL