In the cross hairs of the bill are ordinances passed by Lancaster and 29 other municipalities that require gun owners to report if their gun has been lost or stolen.
and further down says:
Gray said the key word is "lawful." When a gun is lost or stolen, the person who has it is not in lawful possession of it, he said.
But the law is not aimed at the person unlawfully in possession, it is aimed at the gun owner.