At any time after rendition of a verdict of guilty and before sentence, the court may, upon motion of the defendant, set aside or modify the verdict or any part thereof upon the following grounds: 1. Any ground appearing in the record which, if raised upon an appeal from a prospective judgment of conviction, would require a reversal or modification of the judgment as a matter of law by an appellate court. 2. That during the trial there occurred, out of the presence of the court, improper conduct