ESLint build error shouldn't include warnings in the output

[gaearon]

Noticed this with latest canary:

We should filter all warnings out when we fail the build.

[n3tr]

Look like this happen after we added thread-loader. it cause webpack report errors and warnings together as an error.

I tested by remove thread-loader and the output work fine.

[sadkovoy]

I tried to debug, and that's what I found out: with enabled thread-loader webpack returns object stats with following structure

{ "warnings": [], "errors": [/concatenated errors and warnings/] }
So every attempt to differ them like here

create-react-app/packages/react-dev-utils/WebpackDevServerUtils.js

Line 164 in d72678f

if (messages.errors.length) {

will be failed.
Probably it must be fixed in context of thread-loader repo.

[Timer]

This has been resolved in next.