PHP POST请求重定向到root / xampp仪表板

I have a login page with a form with POST method and no action defined (or action to self). I use some functions to do the login, and when some field of the form is left empty or the login credentials are not valid, I´m being redirected to XAMPP dashboard. Its like as if my else statement is not kicking in. Any idea why?

if(ifItIsMethod('post')){

    if(isset($_POST['username']) && isset($_POST['password'])){

        login_user($_POST['username'], $_POST['password']);
    }else{
        echo "bla bla";
    }
}

I tried else{ header(..)} and nothing happens, it just redirects to dashboard.

I have a test version online where the same happens, its here: http://hotfol.com/cms/login_page.php

Thank you!!

Edit: functions

function ifItIsMethod($method=null){

    if($_SERVER['REQUEST_METHOD'] == strtoupper($method)){
        return true;
    }else{
        return false;
    }
}

function login_user($typed_username, $typed_password){
    global $connection;


$typed_username = escape($typed_username);
$typed_password = escape($typed_password);


$query = "SELECT * FROM users WHERE username = '$typed_username'";
$select_user_query = mysqli_query($connection, $query);
if(!$select_user_query) {
    die ("query failed" . mysqli_error($connection));
}

$row = mysqli_fetch_assoc($select_user_query);
    $user_id    = escape($row['user_id']);
    $username   = escape($row['username']);
    $password   = escape($row['user_password']);
    $firstname  = escape($row['user_firstname']);
    $lastname   = escape($row['user_lastname']);
    $user_role  = escape($row['user_role']);


    if (password_verify($typed_password, $password)) {

    $_SESSION['username']  = $username;
    $_SESSION['firstname'] = $firstname;
    $_SESSION['lastname']  = $lastname;
    $_SESSION['user_role'] = $user_role;
    $_SESSION['user_id']   = $user_id;

    header('Location: admin/index.php');
}else{
    header('Location: ../index.php');
    }
}

Your inner if statement is always true, but you cannot login when one is empty. Both username and password are always set, but one of them is empty (still set) and the login_user function receives empty data so it cannot login a user. Use empty() - it shows true when there is an ampty string.