fix: updates error handling to match axios

[electricflannel]

Ran into an issue where we are passing the error message as part of the 400/500 body. The current implementation drops that data, where axios returns the body.

#48

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[electricflannel]

@googlebot I fixed it.

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[electricflannel]

@developit I was wondering if we could get this merged in?

[developit]

Sorry for the delay.

[developit]

Excellent work. Only 3b larger!

[josuemontano]

Thanks for the fix! Would it be possible to have an npm release please?

[gianpaj]

same here. @developit could you make a release, please? 🙏

[gianpaj]

BTW we should add a test, like the one in axios:

should return JSON when rejecting
https://github.com/axios/axios/blob/master/test/specs/requests.spec.js#L234

I don't know how to mock an API call that returns an error message with karmatic
It probably needs to be added to this file:
https://github.com/developit/redaxios/blob/master/test/index.test.js

axios's project is using https://github.com/jasmine/jasmine-ajax - I wonder if need that too