wp_register_script was called incorrectly

You must create a new function hooked to (usually) ‘wp_enqueue_scripts’ so that it fires at the correct time during the WP page load. Otherwise it will fire before WP is ready and will not work (simplified explanation).

Here is an example of a custom function (“jquery_manage_scripts()”) hooked to the ‘wp_enqueue_scripts’ WP action hook, which gets rid of the native WP jQuery and loads a newer version from a public (Google) library.

function jquery_manage_scripts() {

    wp_deregister_script( 'jquery' );
    wp_register_script('jquery', "http" . ($_SERVER['SERVER_PORT'] == 443 ? "s" : "") . "://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js", false, '3.4.1', true);
    wp_enqueue_script( 'jquery' );
}
add_action( 'wp_enqueue_scripts', 'jquery_manage_scripts', 99 );

This code would be added to your (child) theme functions.php file, after you adjust it to suit your needs, more like:

function impreza_manage_scripts() {
    wp_register_script( 'my-script', 'https://url-to-my-script' );
    wp_enqueue_script( 'my-script' );
}
add_action( 'wp_enqueue_scripts', 'impreza_manage_scripts', 99 );

Hopefully this gives you ideas. Learn More about wp_register_script here.