A simple and neat way to get the error level from the error code. You can even customize the error level names further.

<?php
$exceptions = [
        E_ERROR => "E_ERROR",
        E_WARNING => "E_WARNING",
        E_PARSE => "E_PARSE",
        E_NOTICE => "E_NOTICE",
        E_CORE_ERROR => "E_CORE_ERROR",
        E_CORE_WARNING => "E_CORE_WARNING",
        E_COMPILE_ERROR => "E_COMPILE_ERROR",
        E_COMPILE_WARNING => "E_COMPILE_WARNING",
        E_USER_ERROR => "E_USER_ERROR",
        E_USER_WARNING => "E_USER_WARNING",
        E_USER_NOTICE => "E_USER_NOTICE",
        E_STRICT => "E_STRICT",
        E_RECOVERABLE_ERROR => "E_RECOVERABLE_ERROR",
        E_DEPRECATED => "E_DEPRECATED",
        E_USER_DEPRECATED => "E_USER_DEPRECATED",
        E_ALL => "E_ALL"
];

echo $exceptions["1"];
$code = 256;
echo $exceptions[$code];
?>

Output:  
E_ERROR
E_USER_ERROR

This will need updating when PHP updates the error level names. Otherwise, it works just fine.