https://github.com/mongodb/js-bson/pull/322

You can get some nasty surprises when you pass a string to the Decimal128 constructor:

const bson = require('bson');

const v = new bson.Decimal128('14.92');

// {"$numberDecimal":"8.740930561E-6167"}
console.log(JSON.stringify(v));

Would be handy to at least throw an error. Although is there some reason why we can't just do fromString() if the user passes a string instead of a buffer to the Decimal128 constructor?