01lesson ,who can help me~?

[zengqiang24]

npm start

tutorial@1.0.0 start /Users/qiangzeng/react-router-tutorial/lessons/01-setting-up
webpack-dev-server --inline --content-base .

module.js:327
throw err;
^

Error: Cannot find module 'assert/'
at Function.Module._resolveFilename (module.js:325:15)
at Function.require.resolve (internal/module.js:16:19)
at Object. (/Users/qiangzeng/react-router-tutorial/lessons/01-setting-up/node_modules/webpack/node_modules/node-libs-browser/index.js:1:93)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Module.require (module.js:353:17)
at require (internal/module.js:12:17)
at Object. (/Users/qiangzeng/react-router-tutorial/lessons/01-setting-up/node_modules/webpack/lib/node/NodeSourcePlugin.js:7:23)

[zengqiang24]

sorry,I have already solved the problem , please closed.