Update error handling (#7)

utils.go

@@ -20,12 +20,36 @@ func (s *Storage) String() string {
 
 // NewStorager will create Storager only.
 func NewStorager(pairs ...types.Pair) (types.Storager, error) {
+	return newStorager(pairs...)
+}
+
+// newStorager will create a storage client.
+func newStorager(pairs ...types.Pair) (store *Storage, err error) {
+	defer func() {
+		if err != nil {
+			err = services.InitError{Op: "new_storager", Type: Type, Err: formatError(err), Pairs: pairs}
+		}
+	}()
+
 	panic("implement me")
 }
 
+func (s *Storage) formatError(op string, err error, path ...string) error {
+	if err == nil {
+		return nil
+	}
+
+	return services.StorageError{
+		Op:       op,
+		Err:      formatError(err),
+		Storager: s,
+		Path:     path,
+	}
+}
+
 // formatError converts errors returned by SDK into errors defined in go-storage and go-service-*.
 // The original error SHOULD NOT be wrapped.
-func (s *Storage) formatError(op string, err error, path ...string) error {
+func formatError(err error) error {
 	if _, ok := err.(services.InternalError); ok {
 		return err
 	}