The department shall forthwith revoke the license of any operator or chauffeur upon receiving a record of such operator's or chauffeur's conviction of any of the following offenses, when such conviction has become final: Provided, That if the convicted driver had not reached his or her nineteenth birthday at the time of the conduct for which the license is revoked under this section, the license shall be revoked until the driver's nineteenth birthday, or the applicable statutory period of revocation, whichever is longer:
(1) Manslaughter or negligent homicide resulting from the operation of a motor vehicle;