Normally, if a defendant fails to raise an objection in the trial court, he has forfeited his right to raise the claim on appeal. (People v. Yarbrough (2008) 169 Cal.App.4th 303, 310.) "'"No procedural principle is more familiar to this Court than that a constitutional right," or a right of any other sort, "may be forfeited in criminal as well as civil cases by the failure to make timely assertion of the right before a tribunal having jurisdiction to determine it."' 'The purpose of this rule is to encourage parties to bring errors to the attention of the trial court, so that they may be corrected. ' " (In re Sheena K. (2007) 40 Cal.4th 875, 880-881.) But, as a general principle, this forfeiture rule has its exceptions. (Bonner v. City of Santa Ana (1996) 45 Cal.App.4th 1465, 1476.) "On a number of occasions, California courts have held that constitutional issues can be raised for the first time on appeal in various circumstances," such as when a statute is challenged on constitutional grounds. (Id. at pp. 1476-1477; see also In re Sheena K., supra, 40 Cal.4th at p. 884.)