webpack報錯- webpack和webpack-dev-server不兼容

報錯：invalid "instanceof" keyword value Promise 或者Error: Cannot find module 'webpack-cli/bin/config-yargs'

webpack 和webpack-dev-server的版本不兼容

重新安裝和webpack 兼容的webpack-dev-server

自測可行版本：

　　webpack 3.5.5   npm  install  webpack@3.5.5 -g
　　webpack-dev-server 2.11.2    npm install webpack-dev-server@2.11.2