PHP http_response_code($code) gets executed in a totally false if statement

Question

Im developing an API in php, and i ran into a problem, basically http_response_code(int $code); behaviour is unpredictable, it just always gets sent at all costs if present anywhere in the code, and after that, naturally i cannot set another http_response_code(int $otherCode) as headers are already sent. I do not know what i am doing wrong, but i think i can boldly assume that http_response_code(int $code); can be used conditionally because it makes all the sense for me. My question is, how this problem should be solved? I have to use the correct response codes, is there a working alternative which does not use rng to decide if it obeys an if statement?

PHP version is 7.4.5

smol version:

/* CASE 1 */
if(false){
     http_response_code(401);
     echo json_encode($someErrorMessage);
     die;
}
http_response_code(200);
echo json_encode($someResponse);
//Expectation: 200 response code & $someResponse json
//Result: 401 response with no message at all

/* CASE 2 */
if(false){
     //http_response_code(401);
     echo json_encode($someErrorMessage);
     die;
}
http_response_code(200);
echo json_encode($someResponse);
//Expectation: 200 response code & $someResponse json
//Result: 200 response code & json

Actual code:

try{
    if(empty(getallheaders()['Authorization'])){
        throw new WSException("oAuth access token missing from request");
    }
    $user = new Admin(getallheaders()['Authorization']);//Authenticate user, get data(throws WSException)
}
catch(WSException $e){    //Unauthenticated, send 401 header + message
    http_response_code(401);
    echo $e->getMessage();
    die;
}
/* GET USER DATA (SELF) */
#region GET USER DATA (SELF)
if($r == "get_self"){                               //Return user object as json

    try{
        /* BASIC DATA //$user already has all user data after authentication with `new Admin();` */
        if(!empty($user->profile_picture)){         //TODO: Function needed to filePHP
            $user->profile_picture = "{path/to/file.php}".$user->profile_picture;
        }
        http_response_code(200);
        echo json_encode($user, JSON_UNESCAPED_SLASHES);    //Unescaped slashes to send correct urls
        //An error cant really happen here rn, but when there is a possibility, it would be:
        //if($someError){
        //    http_response_code(401);
        //    throw new WSException("Something gone wrong");
        //}
    }catch(WSException $e){
        echo json_encode($e->getMessage());
    }           
    die;
}
#endregion

Answer 1

The actual problem was that empty(getallheaders()['Authorization']) returned true.

var_dump(empty(getallheaders()['Authorization']));
//Result: boolean: false

The thing is, if the value of getallheaders()['Authorization'] is not used, or loaded into a variable, it's actually empty in an if statement

if(empty(getallheaders()['Authorization'])){
     //statement true, code gets executed
}

Solution:

if(empty($authHeader = getallheaders()['Authorization'])){
    //statement false, code does not get executed
}