npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! BitShares2-light@3.1.190604-rc1 start: `cross-env NODE_ENV=development node serve` npm ERR! Exit status 1

Hello, I'm a beginner to bitshares, when I tried to run npm start in /bitshares-ui, it reported a great number of error
`

> BitShares2-light@3.1.190604-rc1 start /home/user1/bitshares-ui
> cross-env NODE_ENV=development node server.js
internal/modules/cjs/loader.js:550
throw err;
^
Error: Cannot find module 'webpack'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:548:15)
at Function.Module._load (internal/modules/cjs/loader.js:475:25)
at Module.require (internal/modules/cjs/loader.js:598:17)
at require (internal/modules/cjs/helpers.js:11:18)
at Object. (/home/user1/bitshares-ui/server.js:2:15)
at Module._compile (internal/modules/cjs/loader.js:654:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
at Module.load (internal/modules/cjs/loader.js:566:32)
at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
at Function.Module._load (internal/modules/cjs/loader.js:498:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! BitShares2-light@3.1.190604-rc1 start: `cross-env NODE_ENV=development node serve`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the BitShares2-light@3.1.190604-rc1 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging outpu.

npm ERR! A complete log of this run can be found in:
npm ERR! /root/.npm/_logs/2019-05-26T16_21_07_535Z-debug.log
`
Here is the package.json
https://raw.githubusercontent.com/bitshares/bitshares-ui/develop/package.json

npm -v
6.9.0

node -v
v9.11.2

The first time I tried to run npm start, it showed cross-env is missed, so I install the cross-env.
I have tried npm start with no cross-env and package.json deleted cross-env, they all failed

Start by checking package.json and server.js, where the reported missing webpack module is loaded, then run the documented npm installation and npm start commands. Done means the BitShares UI starts without the reported missing-module error; the issue does not identify a specific code change.

Written by the indexing model from the issue text.