Another way to catch PHP's fatal errors:

<?php
    error_reporting(E_ALL);
    ini_set('display_errors', 0);

    function shutdown(){
        $isError = false;
        if ($error = error_get_last()){
            switch($error['type']){
                case E_ERROR:
                case E_CORE_ERROR:
                case E_COMPILE_ERROR:
                case E_USER_ERROR:
                    $isError = true;
                    break;
            }
        }

        if ($isError){
            echo "Script execution halted ({$error['message']})";
        } else {
            echo "Script completed";
        }
    }

    register_shutdown_function('shutdown');
?>

Note that this will only catch runtime errors. So calling a method in a non existing class, or declaring a function twice does not trigger the shutdown handler.