I was getting an issue installing brunch today, and this was some of the output
npm http GET https://registry.npmjs.org/node-gyp
npm ERR! Error: SSL Error: CERT_UNTRUSTED
npm ERR! at ClientRequest.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/request/main.js:440:26)
npm ERR! at ClientRequest.g (events.js:185:14)
if you get this try this command
npm config set ca ""