update limits and remove sections about bug

[alexander-akait]

https://github.com/ai/dual-publish#limits

We recommend to avoid default export because of bug in webpack.

It can be misleading because it is not a bug. Explanation - https://github.com/webpack/webpack/issues/7973#issuecomment-419066832 Many other tools (for example babel) work similarly. Even rollup has https://rollupjs.org/guide/en/#outputinterop to control this, because this is a very controversial issue

[ai]

Why Node.js behaviour with CJS to ESM converting for default exports (of module has only default export, export it as object without wrappers) do not work for webpack?

It leads to inconsistency between Webpack and Node.js behaviour and it is the source of the problem.

[alexander-akait]

Using node:

test.mjs

import cjs from './foo.cjs';
import mjs from './foo.mjs';

console.log(cjs);
console.log(mjs);

foo.cjs

// For:
// module.exports = { default: 'cjs' };
//
// output node and webpack is same:
//
// { default: 'cjs' }
module.exports = 'cjs';

foo.mjs

export default 'mjs';

Output:

cjs
mjs

Using webpack

Output:

cjs
mjs

[alexander-akait]

CommonJS doesn't have default export

[ai]

Nope, I am talking about different problem.

You have dual CJS/ESM package:

// lib/index.mjs
export default 'lib'

// lib/index.cjs
module.exports = 'lib'

For Node.js both constructions will work:

require('lib') //=> 'lib'

import lib from 'lib' //=> 'lib'

In Webpack you will have a different result:

require('lib') //=> { default: 'lib' }

It is a open issue and seems like it was fixed in webpack 5, so it is a bug for my understanding of this term. But we can replace this line with recommendations using webpack 5.