Document compatibility steps for Vite integration

Describe the bug

@lingui/core doesn’t provide a valid ESM package. Thus, it can’t work with Vite, which is an ESM based bundler.

node_modules/@lingui/core/esm/index.js will import i18nModule from node_modules/@lingui/core/index.js. However, node_modules/@lingui/core/index.js only export module in CJS way instead of in ESM way.

To Reproduce

$ git clone https://github.com/ocavue/lingui-esm-issue.git
$ cd lingui-esm-issue
$ yarn install 
$ yarn dev 

Open http://localhost:3000 and you can see Uncaught TypeError: Cannot read property 'setupI18n' of undefined in the console.

Expected behavior

No error occurs.

Additional context

• jsLingui version: @lingui/core@3.5.1
• Babel version: @babel/core@7.12.13
• Your Babel config (e.g. .babelrc) or framework you use (Create React App, Meteor, etc.): vite

[a1ooha]

I wrote a plugin for vite and more, which can compiles messages on the fly! It contains a demo for vite integration in the playground catalogs, Hope this helps.

[semoal]

I’ve just started working on this and got it working sucessfully and we should ship this esm packages… but Lingui at least today won’t work on Vite.

Lingui is a library heavily inspired and created above babel-plugin-macros, actually there’s a similar issue for Snowpack integration, so we should decide together an alternative implementation of macros for this new bundlers like vite, esbuild, swc, snowpack… #951

I’ll release the next tuesday anyways a new version with ESM shipping =)