$ npm install -g mathjax-node-cli
npm ERR! Darwin 15.6.0
npm ERR! argv "/usr/local/Cellar/node/7.9.0/bin/node" "/usr/local/bin/npm" "install" "-g" "mathjax-node-cli"
npm ERR! node v7.9.0
npm ERR! npm  v4.2.0
npm ERR! Cannot read property 'path' of null
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>
npm ERR! Please include the following file with any support request:
npm ERR!     /Users/greedo/.npm/_logs/2017-04-19T11_34_12_526Z-debug.log
When inspecting the debug log, I see https://registry.npmjs.org/mathjax-node-cli returns a 404 error