A person shall not be convicted of endangering the welfare of a child, or of an attempt to commit the same, upon the testimony of a victim who is incapable of consent because of mental defect or mental incapacity as to conduct that constitutes an offense or an attempt to commit an offense referred to in section 130.16, without additional evidence sufficient pursuant to section 130.16 to sustain a conviction of an offense referred to in section 130.16, or of an attempt to commit the same.