[#142] Fix multipart-objects download

Signed-off-by: Nikita Zinkevich <n.zinkevich@yadro.com>

internal/service/frostfs/multi_object_reader.go

@@ -173,8 +173,8 @@ func (x *MultiObjectReader) Read(p []byte) (n int, err error) {
 	if x.curReader != nil {
 		n, err = x.curReader.Read(p)
 		if err != nil {
-			if err := x.curReader.Close(); err != nil {
+			if closeErr := x.curReader.Close(); closeErr != nil {
-				return n, err
+				return n, fmt.Errorf("%w (close err: %v)", err, closeErr)
 			}
 		}
 		if !errors.Is(err, io.EOF) {