Build Error on Node 12

I'm getting a build error after merging the changes from PRs to upstream. Don't know enough about NAN to debug this yet.

https://github.com/jandre/node-userid/pull/12
https://github.com/jandre/node-userid/pull/18
https://github.com/jandre/node-userid/pull/22

[2019-11-02T23_32_10_481Z-debug.log](https://github.com/cinderblock/node-userid/files/3801155/2019-11-02T23_32_10_481Z-debug.log)