fix(routes): Allow HMR with warnings

[artembatura]

This PR contains:

• bugfix
• feature
• refactor
• tests
• documentation
• metadata

Breaking Changes?

• yes
• no

If yes, please describe the breakage.

Please Describe Your Changes

We have two message types, which contains information about problems when Application building. There are warnings and errors. Currently when error or warning are detected, webpack-plugin-serve doesn't replace changed files. This PR allow apply changes to files by HMR if get any warning, because warning it's not critical problem, which affect on build process. Warnings never stopping building process. For example, warning from ESLint (eslint-loader)

[shellscape]

curious about this assertion. we're only in need of a truthy/falsy value here. was there an explicit need to case to Boolean?

[artembatura]

Yeah, this doesn't change much using Boolean. It's more stricter perhaps ^o^
And next I simply reuse value

Instead of this:

if (errors.length || warnings.length) {
  ...
  if (errors.length) return;
}

I written:

const hasErrors = Boolean(errors.length);
if (hasErrors  || warnings.length) {
  ...
  if (hasErrors) return;
}