The issue of just compensation shall be determined by a commission or a jury, upon a timely election made by an owner as provided in § 25.1-213. However, by agreement of the petitioner and all the parties who are sui juris that have appeared or responded, or, if no owner upon proper notice has appeared or responded, or has filed an answer and grounds of defense that fails to elect to have the determination of just compensation made by either commissioners or a jury, then, upon motion of the petitioner, the issue of just compensation may be determined by the court.