check http status code

[jasonmacgowan]

Summary

throws errors on http status codes >=400 so the user knows the expected action failed

fixes (kinda) #16

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[jasonmacgowan]

This is a start but really we should be more verbose about what actually failed

Also it's possible to do this by setting something like the following"
curl_setopt($ch,CURLOPT_FAILONERROR,true);

Maybe that's the default for some people and they weren't encountering this?

[fyunaz]

Hi, thanks for looking at this. Are you able to visit the following URL to sign the CLA? https://cla-assistant.io/slackhq/goSDL?pullRequest=17

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