🧹 Capture underlying error on codes.DataLoss (#97)

We are throwing away the underlying error. Capturing it to better
understand why this happens

server.go

@@ -97,7 +97,7 @@ func (s *server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
  return
  }
 
- rctx, rcancel, body, err := preProcessRequest(ctx, req)
+ rctx, rcancel, body, err := preProcessRequest(ctx, span, req)
  if err != nil {
  HttpError(span, w, req, err)
  return
@@ -118,11 +118,12 @@ func (s *server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 // preProcessRequest is used to preprocess the incoming request.
 // It returns the context, a cancel function and the body of the request. The cancel function can be used to cancel
 // the context. It also adds the http headers to the context.
-func preProcessRequest(ctx context.Context, req *http.Request) (context.Context, context.CancelFunc, []byte, error) {
+func preProcessRequest(ctx context.Context, span trace.Span, req *http.Request) (context.Context, context.CancelFunc, []byte, error) {
  // read body content
  body, err := io.ReadAll(req.Body)
  defer req.Body.Close()
  if err != nil {
+ span.RecordError(err)
  return nil, nil, nil, status.Error(codes.DataLoss, "unrecoverable data loss or corruption")
  }