Errors failing to surface when deserializing json

[tvelich]

Client version

6.0.1

Expected behaviour

Errors throw/contain actual reason for request failure

Actual behaviour

Error complains about invalid json (even though content type is text/html): Unexpected end of JSON input at https://github.com/sendwithus/sendwithus_nodejs/blob/master/lib/sendwithus.js#L69

Steps to reproduce

To demonstrate with a 403 just require('sendwithus')().send({}, (err) => console.log(err)) in a node console and it'll fail with this obscure error