As voting begins for Pennsylvania’s general election, legal questions about the ballots of mail-in voters remain unresolved in the swing state that could determine the winner of the presidential race. From what have become known as “undated ballots” to so-called “naked ballots,” the range of issues before state and federal courts center on what to do when voters return absentee ballots on time but don’t follow all of the rules for getting their votes counted. State law requires completed mail-...