d-day 코드오류

강의보면서 그대로 작성했는데 targetDate 부분이 오류가 납니다.

여기서 안되니까 remaining 에서도 오류나고..

콘솔 찍으면 NaN 만 출력이 되네요ㅠㅠ 왜그럴까요?

  <script>
      const dateFormMaker = function () {
        const inputYear = document.querySelector("#target-year-input").value;
        const inputMonth = document.querySelector("#target-month-input").value;
        const inputDate = document.querySelector("#target-date-input").value;

        const dateFormat = `${inputYear}-${inputMonth}-${inputDate}`;

        return dateFormat;
      };

      const counterMaker = function () {
        const targetDateInput = dateFormMaker();
        const nowDate = new Date();
        const targetDate = new Date(targetDateInput).setHours(0,0,0,0); /* error */
        const remaining = (targetDate - nowDate) / 1000;

        const remainingDate = Math.floor(remaining / 3600 / 24);
        const remainingHours = Math.floor(remaining / 3600) % 24;
        const remainingMin = Math.floor(remaining / 60) % 60;
        const remainingSec = Math.floor(remaining) % 60;

        console.log(remainingDate, remainingHours, remainingMin, remainingSec);
        console.log(targetDate);
      };
    </script>