Online PHP editor | output for PLn7o

Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6: Fatal error: Uncaught ArgumentCountError: is_null() expects exactly 1 argument, 0 given in /in/PLn7o:2 Stack trace: #0 /in/PLn7o(2): is_null() #1 {main} thrown in /in/PLn7o on line 2
Process exited with code 255.
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33: Warning: is_null() expects exactly 1 parameter, 0 given in /in/PLn7o on line 2 bool(false) bool(true) Warning: is_null() expects exactly 1 parameter, 2 given in /in/PLn7o on line 2 bool(false) Warning: is_null() expects exactly 1 parameter, 3 given in /in/PLn7o on line 2 bool(false)
Output for 4.3.2 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17: Warning: is_null(): Only one argument expected in /in/PLn7o on line 2 bool(false) bool(true) Warning: is_null(): Only one argument expected in /in/PLn7o on line 2 bool(false) Warning: is_null(): Only one argument expected in /in/PLn7o on line 2 bool(false)
Output for 4.3.0 - 4.3.1: Warning: is_null() [http://www.php.net/function.is-null]: Only one argument expected in /in/PLn7o on line 2 bool(false) bool(true) Warning: is_null() [http://www.php.net/function.is-null]: Only one argument expected in /in/PLn7o on line 2 bool(false) Warning: is_null() [http://www.php.net/function.is-null]: Only one argument expected in /in/PLn7o on line 2 bool(false)