$image_size = 'full'; // Fallback.
$meta = wp_get_attachment_metadata( $thumbnail_id );
- if ( is_array( $meta ) ) {
+ if ( ! empty( $meta['sizes'] ) ) {
foreach ( $meta['sizes'] as $size => $data ) {
if ( $data['width'] / $data['height'] > $aspect_ratio ) {
$aspect_ratio = $data['width'] / $data['height'];