安装Angular2时出现此错误
npm ERR! Windows_NT 10.0.14393
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "-g" "angular-cli"
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:\angular2-demo\npm-debug.log
如何解决这个问题