Missing HTTP error handling

[TheHalcyonSavant]

I can't find the superagent error callback, it seems it's forgotten the usage of err parameter here. Do you accept PR for this?

[alebell]

I wanted to report this too. It would be great if the error handling could be implemented properly.

[callumacrae]

A PR would be good! 😄

[backflip]

Would you prefer changing the API to expect callback: function(err, res) or keep callback: function(res) and let the consumer check whether res is of type Error?

[backflip]

@callumacrae, which approach would you prefer?

[jhermsmeier]

HTTP request error handling has been added in #32 (published as 0.3.1) – the callback will get an error as its first argument, i.e. callback: function(error, res) now