Почему не работает mysqli_query() и mysqli_fetch_all()

Источник https://www.youtube.com/watch?v=Z_5RGo38cdc&list=LLHgPabR2InepdgXHIaptdsQ&index=5&t=962s
Код выглядит так,

    <?php
     $mysqli = new mysqli('localhost','...','...','...');
    if (!$mysqli){
        die("Connaction failed" .mysqli_connect_error());
    }
    function get_posts() {
        global $musqli;
        $sql = "SELECT * FROM posts";
   "line6" $result = mysqli_query($musqli, $sql);
   "line7" $posts = mysqli_fetch_all($result, MYSQLI_ASSOC);
        return $posts;
    }
                    <pre><?php var_dump($posts) ?></pre>
                <?php 
                $posts = get_posts ();
                 ?>
        "line 78"        <?php foreach ($posts as $post) : ?>
                 ДИВ В КОТОРОМ ПОДСТАВЛЕНЫ ПАРАМЕТРЫ
                <?php endforeach; ?>

Ошибка Warning: mysqli_query() expects parameter 1 to be mysqli, null given in D:\OpenServer\OSPanel\domains\Project2\Index.php on line 6

Warning: mysqli_fetch_all() expects parameter 1 to be mysqli_result, null given in D:\OpenServer\OSPanel\domains\Project2\Index.php on line 7

Warning: Invalid argument supplied for foreach() in D:\OpenServer\OSPanel\domains\Project2\Index.php on line 78