Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
오류 발생시 해당 경로로 터미널 이동후
rm -f ./.git/index.lock입력하면 끝.
개발자입니다.