This chapter shall not apply to a sheriff, constable, police
officer or their deputies while in performance of the duties of their
respective offices.
Any person who shall violate any provision of this chapter shall, upon conviction thereof, be subject to a penalty as provided in §
1-3 of this Code, provided that for a first offense any person 18 years of age or under who shall be found violating the provisions of this chapter shall be warned of the penalty for such violation by a law enforcement officer and shall be taken and delivered to the custody of the person having legal custody over him, and for a second or subsequent offense he shall be dealt with according to the provisions of Ch. 48, Wis. Stats.