This will make it possible for packages dependant on graphql to in turn do the same for their consumers, without encountering babel/babel#7294.

Node.js with --experimental-modules can run ESM in .mjs files.

Essentially, package.json needs to go from this:

{ "main": "index.js", "module": "module/index.js" }

To this:

{ "main": "index", "module": "index.mjs" }

Sibling index.js (CJS) and index.mjs (ESM) files need to be published. Node.js will load the relevant file, looking up .mjs before .js for main if --experimental-modules is enabled.