React 설치 오류 해결
info No lockfile found. error Running this command will add the dependency to the workspace root rather than the workspace itself, which might not be what you want - if you really meant it, make it explicit by running this command again with the -W flag (or --ignore-workspace-root-check). info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.
오류 해결 방법
yarn add react@17.0.2 -W
or
yarn add react@17.0.2 --ignore-workspace-root-check