Built-in themes are not working with 3.0.13

Description

The built-in themes are not working with v3.0.13.

Steps to reproduce

1. npm init
2. npm i -D [email protected]
3. set start script
4. create deck.mdx and copy-paste the code below
5. npm start
6. nothing shown

import { themes } from "mdx-deck";
export const theme = themes.dark;

# Hoge

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fuga

Workaround & Notes

It is working with v3.0.8. With v3.0.13, it seems that the dark.js is loaded but then the body of the html is gone.