Importing core-js/modules/es.promise causes Promise.finally to be undefined

[plaa]

I am using Storybook with React Native. I discovered that after Storybook was imported Promise.prototype.finally became undefined. I hunted the problem down to Storybook performing:

import 'core-js/modules/es.promise';

Before the import Promise.prototype.finally is a function, after the import it is undefined (but other promise functions work as expected). Example repo.

I tried also import 'core-js/features/promise' - this changes Promise.prototype.finally from a JS function to native code function and seems to work.

I am unsure whether this is a bug in core-js or in the way Storybook is using core-js.

[zloirock]

Yes, with the current logic also should be imported core-js/modules/es.promise.finally. /modules/ path not for direct usage - it should be used by entry points like core-js/es/promise or tools like @babel/preset-env and it should inject required modules.

[plaa]

In case someone else hits this, I eventually found Storybook #8371. If I understand it correctly, Storybook includes incorrect polyfills in the RN code due to build issues.

Thanks.