<?php

/* BEST ?

if($isError1) {
    doStepOne();
    if(!$isError2) {
        doStepTwo();
    } else {
        header("HTTP/1.1 415 Unsupported Media Type");
        trigger_error("HTTP/1.1 415 Unsupported Media Type", E_USER_ERROR);
        exit;
    }
} else {
    header("HTTP/1.1 415 Unsupported Media Type");
    trigger_error("HTTP/1.1 415 Unsupported Media Type", E_USER_ERROR);
    exit;
}

/* VERSUS */

if($isError1) {
    header("HTTP/1.1 415 Unsupported Media Type");
    trigger_error("HTTP/1.1 415 Unsupported Media Type", E_USER_ERROR);
    exit;
}

doStepOne();

if($isError2) {
    header("HTTP/1.1 415 Unsupported Media Type");
    trigger_error("HTTP/1.1 415 Unsupported Media Type", E_USER_ERROR);
    exit;
}

doStepTwo();