Consider including response body in ErrorResponse message

[tnajdek]

Currently ErrorResponse (which extends Error) is thrown for failed requests. Message (which is usually immediately available, e.g. printed on console), consists of status code and status text, e.g. 412: Precondition Failed. It would be more helpful if it actually included response body which usually contains a hint what went wrong, e.g. 412: Precondition Failed. The file has changed remotely since retrieval.