My coupon checking codewars program has an unexplained error

function checkCoupon(enteredCode, correctCode, currentDate, expirationDate) {
  const months = 'January February March April May June July August September October November December'.split(' ');
  if (enteredCode != correctCode) return false;
  
  if (Number(currentDate.split(' ')[2]) > Number(expirationDate.split(' ')[2])) return false;
  
  else if (Number(currentDate.split(' ')[2]) == Number(expirationDate.split(' ')[2])) {
    for (let x = 0; x < months.length; x++) {
      if (months[x] == currentDate.split(' ')[0]) {
        for (let y = 0; y < months.length; y++) {
          if (months[y] == expirationDate.split(' ')[0]) {
            if (x > y) return false;
            else if (x == y) {
              if (Number(currentDate.split(' ')[1].replace(',', '')) > Number(expirationDate.split(' ')[1].replace(',', ''))) return false;
              else return true;
            }
            else return true;
          }
        }
      }
    }
  }
  
  else return true;
}