Handle non-JSON 404 Response on Session.renew PUT request

[rodoyle]

When Session::renew yields a 404 response Response: '404 Not Found' for http://localhost:8500/v1/session/renew/f933ddd8-c5a6-5d7e-898e-95fc8aebaadb? to a PUT request,
the client will return the following JSON parse error
Error(Msg("Failed to parse JSON"), State { next_error: Some(Error(Json(Error("expected value", line: 1, column: 1)))), backtrace: InternalBacktrace { backtrace: None } }

This is likely because the error responses are not valid JSON.