[section04] cd class 이후 react 버전 변경시 오류

cd class 이후 react 버전 변경 시 아래와 같은 오류가 진행됩니다. 어떻게 해결해야할까요..ㅠㅠ

Usage Error: The nearest package directory (C:\Users\user\Desktop\CodeCamp_Frontend_j\class) doesn't seem to be part of the project declared in C:\Users\user.

- If C:\Users\user isn't intended to be a project, remove any yarn.lock and/or package.json file there.

- If C:\Users\user is intended to be a project, it might be that you forgot to list Desktop/CodeCamp_Frontend_j/class in its workspace configuration.

- Finally, if C:\Users\user is fine and you intend Desktop/CodeCamp_Frontend_j/class to be treated as a completely separate project (not e