Yarn を使用してインストールしようとnpm installすると、上記のディレクトリで package.json の検索に失敗します。
npm ERR! addLocal Could not install /Users/user/Developer
npm ERR! Darwin 16.1.0
npm ERR! argv "/usr/local/Cellar/node6-lts/6.9.1/bin/node" "/usr/local/bin/npm" "install"
npm ERR! node v6.9.1
npm ERR! npm v3.10.9
npm ERR! code EISDIR
npm ERR! errno -21
npm ERR! syscall read
npm ERR! eisdir EISDIR: illegal operation on a directory, read
npm ERR! eisdir This is most likely not a problem with npm itself
npm ERR! eisdir and is related to npm not being able to find a package.json in
npm ERR! eisdir a package you are trying to install.
npm ERR! Please include the following file with any support request:
npm ERR! /Users/user/Developer/npm-debug.log
なぜこれが起こっているのかについて何か考えはありますか？