Plaintiff P lost all sight in one eye and most of the sight in his other eye after undergoing back surgery at defendant medical center. When the trial court excluded testimony from his retained experts due to discovery violations, P decided to proceed on a theory of res ipsa loquitur. After a hearing, the court ruled that P had not made out a prima facie case of negligence under this theory and granted D's motion for nonsuit. (See Curtis v Santa Clara Valley Med. Ctr. (2003) 110 CA4th 796.) a) Did the trial court err in excluding the expert testimony?