npm ERR! Refusing to delete /usr/local/bin/yarn: node_modules/npm/bin/npm-cli.js symlink target is not controlled by npm /usr/local
npm ERR! File exists: /usr/local/bin/yarn
npm ERR! Move it away, and try again.
Recently yarn was added to the Docker images. If you are trying to install yarn via npm, remove the yarn from your npm install or your package.json.
Yarn has been included for quite a while. I don't think this is needed anymore
rm -rf /usr/local/bin/yarn
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rm -rf /usr/local/bin/yarn