Seems to be broken with Node 10.9.0

[nikgraf]

I'm running the example and it fails with

TypeError [ERR_INVALID_RETURN_PROPERTY]: Expected a valid url to be returned for the "url" from the "loader resolve" function but got ./addTwo.wasm.
    at Loader.resolve (internal/modules/esm/loader.js:84:15)

I believe some internals changed and the loader needs to be updated. In best case I can look into it. This seem to be the related code in Node: https://github.com/nodejs/node/blob/master/lib/internal/modules/esm/loader.js#L80-L88