C:\Users\wei.peng>npm install -g typescript
npm ERR! Windows_NT 6.1.7601
npm ERR! argv "C:\Program Files\nodejs\node.exe" "C:\Program Files\nodejs\
node_modules\npm\bin\npm-cli.js" "install" "-g" "typescript"
npm ERR! node v7.4.0
npm ERR! npm v4.0.5
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! C:\Users\wei.peng\npm-debug.log
