fatal error on WP 4.7

PHP Fatal error: Cannot use object of type WP_Error as array in
/var/www/jeumoba.fr/wp-content/plugins/easing-slider/src/Plugin/Support/AttachmentImageResizer.php on line 131,

There come the lines:
// Get resized image information
$resizedUrl = str_replace(basename($attachmentUrl), basename($saved[‘path’]), $attachmentUrl);
$resizedWidth = $saved[‘width’];
$resizedHeight = $saved[‘height’];
$resizedType = $saved[‘mime-type’];