Missing exports field causing packge to be incompatible with ESM

[jmrossy]

The package.json should have an exports field that matches the parts of the files list that may be imported into JS code. JS tooling (typescript, bundlers, vscode) tends to forgive the missing field when the consuming package isn't using ESM modules but imports will fail when they are using ESM.

Also the files field looks incorrect to be but I may be missing something. It's pointing to files and folders at the root that don't exist.

A useful resource to learn more about this: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c#how-can-i-make-my-typescript-project-output-esm