Issue 90 let code be in error response

[curtis741]

What is the current behavior?

code is not included when using the jsonapi_errors renderer

What is the new behavior?

code is included when using render jsonapi_errors

Checklist

I couldn't actually run the tests with a clean checkout from master on 2.0.1.

Also I don't see any tests for render jsonapi_errors? maybe I'm missing it...

Please make sure the following requirements are complete:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes /
  features)
• All automated checks pass (CI/CD)

[stas]

Also I don't see any tests for render jsonapi_errors? maybe I'm missing it...

Please take a look at this one:
https://github.com/stas/jsonapi.rb/blob/master/spec/errors_spec.rb

[curtis741]

@stas I saw that file, all of those tests were testing the rendering of a resource that had an error. But there were no tests when you call jsonapi_error without a resource.

It's cool, I got a new test all setup so you've now got more test coverage.

[curtis741]

@stas does this PR look good now?

[curtis741]

@stas any feedback on this PR?

[curtis741]

thanks @stas !