If a defendant cross-examines a witness through an appointed person, the court must issue a warning to the jury (if any) to the effect that:
(a) the procedure is a routine practice of the court; and
(b) no adverse inference is to be drawn against the defendant as a result of the use of the arrangement; and
(c) the evidence of the witness is not to be given any greater or lesser weight because of the use of the arrangement.