Вынесена в константу ошибка при удалении языка, который является fallback в Locales API

pkg/locales/errors.go

@@ -17,4 +17,5 @@ var (
 	ErrDisablePublishingDefaultLocale = errors.New("cannot disable publishing for default locale")
 	ErrSetDefaultLocaleFallback       = errors.New("cannot set fallback for default locale")
 	ErrDeleteDefaultLocale            = errors.New("cannot delete default locale")
+	ErrDeleteFallbackLocale           = errors.New("cannot delete locale that is used as fallback for other locales")
 )