WP_debug errors with wp_enqueue

Solution:

Use the wp_enqueue_scripts action to call this function, or admin_enqueue_scripts to call it on the admin side.

To load it for front end, use

add_action('wp_enqueue_scripts', 'my_scripts_method');
function my_scripts_method() {
    wp_enqueue_script('jquery');
}

To load it for admin, use

add_action('admin_enqueue_scripts', 'my_admin_scripts_method');
function my_admin_scripts_method() {
    wp_enqueue_script('jquery');
}

Reference: Codex.