Officials across New Jersey agree that 2020’s mostly mail-in election — the biggest and most complex in state history — was also the most successful, as 4.5 million people voted safely in the midst of a public-health crisis. Lawmakers had hoped to build on that success by moving quickly with a plan that would bring early in-person voting to New Jersey as soon as this year’s gubernatorial primary, scheduled for June 8. Early voting already takes place in more than half the states, but for now the bill is stalled. To make early voting happen, New Jersey needs to update its voter registration system. That system is a complex web of computer servers and software linking all 21 counties with agencies in Trenton, including the division of elections, Motor Vehicle Commission and central offices for state courts, corrections and human services. It’s supposed to keep accurate track of registered voters and their addresses.