Display a fallback Alt tag if none is present. Ideally clients should be instructed on how to add media with the relevant alt tags.

Display a fallback Alt tag

/**
 * Display a fallback Alt tag if none is present. Ideally clients should be instructed on how to add media with the relevant alt tags.
 */
function sz_wp_get_attachment_image_attributes ( $attr, $attachment, $size ) {
    global $post;


    if ( empty($attr['alt']) ){
        // $attr['alt'] = 'hardcord fallback';
        // $attr['alt'] = get_field('heading', $post->ID);
        // $attr['alt'] = $post->post_title;
    }
    return $attr;
}
add_filter('wp_get_attachment_image_attributes', __NAMESPACE__ . '\\sz_wp_get_attachment_image_attributes', 10, 3 );