fix: Explicit filepath

[jimmywarting]

You are not truly using ESM unless you are not specifying the extension.
you are compiling to commonjs after all...

remote http path resolver (like http-import) don't have access to the filesystem and can't resolve ./foo to ./foo.js or ./foo/index.js it's unable to guess what you meant

https://nodejs.org/docs/latest-v17.x/api/esm.html#mandatory-file-extensions

the only thing i think you have left to do is adding "type": "module" in package.json and stop generating cjs/umd and just output esm, but this is up to you - at least now this is more cdn friendly

[aearly]

Thanks. ESM support has changed out from underneath us since we did the initial switch to ESM.