Version

4.5.0

Environment info

-

Steps to reproduce

According to https://github.com/vuejs/vue-cli/blob/master/packages/@vue/cli-service/lib/commands/serve.js the devtool option for webpack in non-production mode is 'eval-cheap-source-map'.

But I do not find any information about this type of value in the webpack docs or code

• https://github.com/webpack/webpack/blob/master/examples/source-map/webpack.config.js
• https://webpack.js.org/configuration/devtool/

What is expected?

A valid devtool option

What is actually happening?

An invalid devtool option is used.