Exported PropTypes shapes get lost in translation

Tái hiện lệnh microbundle đã được báo cáo với import LocaleShape dùng chung và kiểm tra bundle được tạo, trong đó shape PropTypes được export trở thành null. So sánh với build đang hoạt động, trong đó shape được nhân đôi; hoàn tất khi các shape được import vẫn hợp lệ và cảnh báo prop-type của React không còn báo expected one of [null,null].

Hi there,
Thank you for the great work you've done with microbundle. For the record, here is how I'm using the lib:
microbundle --jsx React.createElement --no-compress --format modern,cjs

I'm using react in version 17 and microbundle in version 0.12.0-next.9

I've got a PropType shape that is used in several definitions:

import PropTypes from "prop-types";

 const LocaleShape = PropTypes.shape({
    // two-char language code ("en", "fr", "de")
    tag: PropTypes.string.isRequired,
    // human readable language description
    language: PropTypes.oneOf([PropTypes.object, PropTypes.string]).isRequired,
    //latin, cyrillic, etc.
    script: PropTypes.string,
    // two-char region code ("US", "CA", "GB", "CH")
    region: PropTypes.string,
    // text direction / orientation: right to left, left to right
    orientation: PropTypes.oneOf(["rtl", "ltr"]),
    // optional emoji string for displaying a flag 🇨🇬 🇲🇼 🇹🇩
    flag: PropTypes.string,
    // String that can be used to search for a locale
    keywords: PropTypes.string,
    // locale identifier of the fallback locale
    fallback: PropTypes.string,
    // optional identifier. If not specified, locale identifier will result in the concatenation
    // of tag and region, with a dash separator: "en-GB", "fr-CA", "nl-BE"
    id: PropTypes.string,
});
export default LocaleShape;

This shape is imported in different files:

LocaleChooser.propTypes = {
  value: PropTypes.oneOfType([LocaleShape, PropTypes.arrayOf(LocaleShape)]),
  locales: PropTypes.arrayOf(LocaleShape),
}

When the bundle is built, it looks like the exported PropType shape is turned into null, as explain the warnings I receive in console:

Warning: Failed prop type: Invalid prop `locales[0].language` of value `[object Object]` supplied to `LocaleChooser`, expected one of [null,null].

This warning is suppressed once I remove the imports and duplicate the LocaleShape in every file that requires it. Am I missing a parameter in the command?

Thanks for your help