Webpack Dev Server should update to a new version

[lwxbr]

Version

3.9.2

Reproduction link

webpack/webpack-dev-server#2158

Environment info

Webpack Dev Server: 3.1.4
Webpack: 4.15.1

Steps to reproduce

Read the link and you will understand the problem.

What is expected?

The Webpack Dev Server should run without problem.

What is actually happening?

There is a problem in validation of liveReload option.

---

Please, read that thread and you will understand why the update is needed: webpack/webpack-dev-server#2158

See also: #4368

[haoqunjiang]

vue-cli/packages/@vue/cli-service/package.json

Line 80 in c36eabc

"webpack-dev-server": "^3.4.1",

I think it's due to your local npm cache.
Please remove package-lock.json, run npm cache clean -f and then rerun npm install in the project directory.

Also, next time, please provide a reproduction.