According to the NJ law cited the Governor would appoint someone to fill the vacancy until the next general election as provided by law- two years later. That winner would serve the 4-year reminder of the term.
There is no 17th amendment problem, as it is being done as provided by the state legislature.
Though it seems a fundamental Constitutional right-to-vote consideration should prevent this barbarity, I don't see how!
The New Jersey Supreme Court has a 4-3 Democratic majority. Think they can't come up with a cockamamie theory to ignore plainly written law?