Cannot use locale-enum with webpack

[dimatomp]

The following code shows an error when I try adding locale-enum to webpack bundle.

import { Locale } from "locale-enum";
export type Lang = Locale.en | Locale.ja;

The error message is,

ERROR in /.../src/common/utils/Lang.ts
./src/common/utils/Lang.ts
[tsl] ERROR in /.../src/common/utils/Lang.ts(3,20)
      TS2503: Cannot find namespace 'Locale'.

ERROR in /.../src/common/utils/Lang.ts
./src/common/utils/Lang.ts
[tsl] ERROR in /.../src/common/utils/Lang.ts(3,32)
      TS2503: Cannot find namespace 'Locale'.

I will be happy to know if there is a standard workaround for this kind of issues though.