Add main module field

[aayla-secura]

This is the same issue as #22 and #14. I'm just opening a new one as they haven't really been resolved. Yes, this suggests adding cjs extensions to the resolver but it still doesn't really work in Metro bundler (at least not in my setup, tried). The problem is that metro bundler doesn't support exports and needs main. What does work and what the proper solution is, is for copy-anything (and your other packages including is-what) to just add a main field to package.json:

--- a/copy-anything/package.json	2025-12-10 16:51:35.153764705 +0000
+++ b/copy-anything/package.json	2025-12-10 16:50:49.741779711 +0000
@@ -4,6 +4,7 @@
   "description": "An optimised way to copy'ing an object. A small and simple integration",
   "type": "module",
   "sideEffects": false,
+  "main": "./dist/index.js",
   "exports": {
     ".": "./dist/index.js"
   },

[mesqueeb]

@aayla-secura given that this is not a requirement for purely ESM packages, I am thinking it's an upstream issue in metro bundler.

[aayla-secura]

@mesqueeb Well, lack of export support in Metro is just a missing feature and not a bug. Yes, I agree it would be great if they supported it (and I think it is in the process of being supported), but given that the main field is standard, most widely supported, the vast majority of node packages do define it, and there is no harm or difficulty in adding it, then I don't see why not just add it as it would solve the issue for so many React native users.