handle more error cases

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

error.go

@@ -9,32 +9,46 @@ func microError(err error) error {
 	// no error
 
 	if err == nil {
+		// nothing to do
 		return nil
 	}
 
 	if verr, ok := err.(*errors.Error); ok {
+		// micro error
 		return verr
 	}
 
 	// grpc error
 	s, ok := status.FromError(err)
 	if !ok {
+		// can't get status detals from grpc error, return base error
 		return err
 	}
 
 	details := s.Details()
 	switch len(details) {
 	case 0:
+		if verr := errors.Parse(s.Message()); verr.Code > 0 {
+			// return micro error
+			return verr
+		}
+		// return base error as it not micro error
 		return err
 	case 1:
-		if verr, ok := details[0].(error); ok {
+		if verr, ok := details[0].(*errors.Error); ok {
-			return microError(verr)
+			// return nested micro error
-		}
+			return verr
-		return err
-	default:
-		if e := errors.Parse(s.Message()); e.Code > 0 {
-			return e // actually a micro error
 		}
+		// return base error as it not holds micro error
 		return err
 	}
+
+	// attached messages in details more then 1, try to fallback to micro error
+	if verr := errors.Parse(s.Message()); verr.Code > 0 {
+		// return micro error
+		return verr
+	}
+
+	// not micro error return base error
+	return err
 }