[FEATURE] Show HTTP Body in case of an error, e.g. Bad Request 400

What / Why

Using a repository other than the NPM registry, e.g. Gitlab's package registry, there are several different reasons, why HTTP response STATUS codes could be other than 200.

When

• Try to publish an npm package to a Gitlab's project registry
• The package has already been published to another Gitlab project on the same instance
• HTTP Status code will be 400 and the response's body contains the relevant information being "message: 'Validation failed: Package already exists'"
• NPM registry fetch does hide this information, even when ran in verbose mode, so you only get informed about the HTTP Status code

Where

• Gitlab's package registry

Current Behavior

You'll only get presented an information like this

npm ERR! code E400
npm ERR! 400 Bad Request - PUT https://someUrl

Expected Behavior

checkErrorsin check-response.js should print the message's body to the console, if not empty and thereby provide more information send by the specific registry system.

Start in check-response.js at checkErrors, which the issue identifies as the relevant entry point. Reproduce the GitLab package-registry 400 response described in the issue and inspect how the response body is handled. Done means a non-empty error body is shown alongside the HTTP error details without changing the existing status reporting.