Restore main field in package.json

[mgcrea]

ky@0.28.0 can't be used in react-native apps anymore due to a missing main field in package.json.

Metro does provide configuration options to support extra "main" fields but adding "exports" there breaks as other packages start to use this field instead of their "main" (not sure why, as it is expected to be an ordered check, maybe a metro-related bug of the "exports" key handling when in object form). Haven't found a way to make it work except manually patching the ky's package.json.

error: Error: While trying to resolve module `ky` from file `~/foo/src/services/pumalocal/client.ts`, the package `~/foo/node_modules/ky/package.json` was successfully found. However, this package itself specifies a `main` module field that could not be resolved (`~/foo/node_modules/ky/index`. Indeed, none of these files exist:

[sholladay]

Issue #340 mentions other tools that are also breaking due to lack of main.

I'm personally in favor of merging this fix. Though, I'd really like to understand the root cause first. Ky is a valid package and Node's require() function can handle our usage of exports, so what are these tools doing that's causing problems?

[mgcrea]

I'm personally in favor of merging this fix. Though, I'd really like to understand the root cause first. Ky is a valid package and Node's require() function can handle our usage of exports, so what are these tools doing that's causing problems?

I think webpack or metro are designed to actively check specific keys in your package.json in a specific, user-configurable order, (eg. ['browser', 'module', 'main']) and bypass node require(). One use-case was to enable tree-shaking with the non-official "module" key before the "exports" field was spec'ed.

[sholladay]

Sure, I am aware of that behavior and it's a good point that the problem likely stems from how they detect which key to use. However, I would expect that once they find the exports key, they would pass its value to require(), which should work. Perhaps the implementation is more complicated than that, though.

[sholladay]

As I mentioned in #340 (comment), importing Ky from the unpkg CDN is also broken and I believe it's a similar root cause, meaning this will likely fix that, too. It would seem that a lot of the ecosystem is just implementing their own algorithms for finding the main entry point instead of using Node's require.resolve() or anything even remotely standardized.

[lpellegr]

I experienced the same issue using the last version of ky with a Typescript web app and ESM imports. This PR fixes the issue.

[mgcrea]

@sindresorhus any chance you could merge & release quickly this change as it is breaking many setups? Thanks!

[sindresorhus]

Sorry for the slow reply. Somehow I got accidentally unsubscribed to the Ky repo.

https://github.com/sindresorhus/ky/releases/tag/v0.28.2