WordPress ACFNotice: get_field() - We've detected one or more calls to retrieve ACF field values before ACF has been initialized

PHP Snippet 1:

add_action( 'acf/init', 'custom_code' );

function custom_code() {
    acf_add_local_field_group(array(
        'key' => 'group_1',
        'title' => 'Page Hero',
        'fields' => array (
            array (
                'key' => 'field_1',
                'label' => 'Hero Title',
                'name' => hero_title,
                'type' => 'text',
            )
        ),
        'location' => array (
            array (
                array (
                    'param' => 'post_type',
                    'operator' => '==',
                    'value' => page,
                ),
            ),
        ),
    ));
}