Pull request #94 causes http.ErrBodyReadAfterClose

[lagren]

I have experienced a bug that is mentioned by @faulkner in #94 (https://github.com/getsentry/sentry-go/pull/94/files#r373130154)

This introduces a new bug. If ioutil.ReadAll returns an error the body is left in a closed state, so reading the body later results in a http.ErrBodyReadAfterClose, so instead of the original error getting sent to Sentry you end up just getting http: invalid Read on closed Body with no way of knowing what the original error was.

According to a follow-up comment, this would be addressed in #117. But that issue was closed without any code changes and I don't see any other issues opened to keep track of this bug.

[rhcarvalho]

@lagren I have a WIP that will address that (this) and #96.

[rhcarvalho]

@lagren could you please try with master?

I'm planning to cut v0.6.0 soon.