在vue cli3.0 里面下载less，下载成功了还是提示没有 需要下载

今天正好新建了一个项目，在用less的时候就各种花样报错提示我：

Failed to resolve loader: less-loader

You may need to install it.

Error from chokidar (C:\): Error: EBUSY: resource busy or locked, lstat 'C:\hiberfil.sys'

Error from chokidar (C:\): Error: EBUSY: resource busy or locked, lstat 'C:\pagefile.sys'

Error from chokidar (C:\): Error: EBUSY: resource busy or locked, lstat 'C:\swapfile.sys'

Failed to resolve loader: less-loader

You may need to install it.

Error: Cannot find module 'less'