Missing esm dirs cause build error

[cherealnice]

Hi!

I was trying out Vite and I got this error when building:
Failed to resolve entry for package "@mathdoy/toggle". The package may have incorrect main/module/exports specified in its package.json

After some digging it seems like the module setting in package.json is set to:
"module": "esm/toggle.js",

After running npm i, these esm directories do not exist which is causing this error. Removing the module field resolves the issue.

Happy to open a PR, just wasn't sure what the best path forward is for this, one solution is to nuke the module fields, another is to build esm and include them into the packages.

versions:
@mathdoy/toggle: 1.1.0
@mathody/toggle-react: 1.1.2