Online PHP editor | output for Tpkaf

Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7: Fatal error: Uncaught TypeError: array_key_exists(): Argument #2 ($array) must be of type array, null given in /in/Tpkaf:6 Stack trace: #0 {main} thrown in /in/Tpkaf on line 6
Process exited with code 255.
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33: Warning: array_key_exists() expects parameter 2 to be array, null given in /in/Tpkaf on line 6 NULL
Output for 5.2.3 - 5.2.17: Warning: array_key_exists(): The second argument should be either an array or an object in /in/Tpkaf on line 6 bool(false)
Output for 4.4.3 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.2: Warning: array_key_exists() [<a href='function.array-key-exists'>function.array-key-exists</a>]: The second argument should be either an array or an object in /in/Tpkaf on line 6 bool(false)
Output for 4.3.2 - 4.3.11, 4.4.0 - 4.4.2: Warning: array_key_exists(): The second argument should be either an array or an object in /in/Tpkaf on line 6 bool(false)
Output for 4.3.0 - 4.3.1: Warning: array_key_exists() [<a href='http://www.php.net/function.array-key-exists'>function.array-key-exists</a>]: The second argument should be either an array or an object in /in/Tpkaf on line 6 bool(false)