에러 메시지
next : The term 'next' is not recognized as the name of a cmdlet, function, script file, or operable pro
gram. Check the spelling of the name, or if a path was included, verify that the path is correct and try
again.
-> next가 없다는 의미 이므로 설치해주면 됨
해결 방법
npm install next -g
