npm ERR! code ENOSELF
npm ERR! Refusing to install package with name "webpack" under a package
npm ERR! also called "webpack". Did you name your project the same
npm ERR! as the dependency you're installing?
说明你执行命令的目录里有一个package.json文件，并且该文件里的name字段就叫webpack。
换个名字就好了