同时出现3个错误：未定义的索引，mysqli_fetch_array需要参数1并尝试获取非对象的属性[重复]

Got these 3 errors and I do not know what to do. Looked up here, none helped me. Here are the errors I'm getting:

Notice: Undefined index: id on line 39

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, bool given on line 40

Notice: Trying to get property 'username' of non-object on line 44

I'm using PHP version 7.3.8 and XAMPP.

<?php
$host = "localhost"; // db host
$user = "root"; // db user
$pass = ""; // db password
$name = "23812"; // db name
$conn = new MySQLi($host, $user, $pass, $name);

// errors

if ($conn->connect_errno) {
    die("ERROR : -> " . $conn->connect_error);
}

// =====

// session

if(session_status() == PHP_SESSION_NONE) {
    session_name("SiteSess");
    session_start();
}

// =====


// date

date_default_timezone_set("America/New_York"); // EST.
$time = date("Y-m-d - h:ia"); // Current timestamp.
$date = time();


// =====

// user variables

$loggedIn = isset($_SESSION['id']);

$query = $conn->query("SELECT * FROM users WHERE id=" . $_SESSION['id']);
$userRow = mysqli_fetch_array($query);

$CurrentUser = $conn->query("SELECT * FROM users WHERE id='".$userRow['id']."'");
$user = mysqli_fetch_object($CurrentUser);
$username = $user->username;

// =====
?>

</div>