usemaps gives undefined instead

[SanderElias]

I'm looking into this for the base of my library. I have no control over what data I need to handle later on, other as the requirement "All js types should be supported"

import { encode, decode, createCodec } from 'msgpack-lite';
const options = { codec: createCodec({ usemap: true, preset: true }) };

const test = Array.from({ length: 10 }, (e, i) => ({
  name: i + ' sander',
  dob: new Date(1900, 4, 14),
  stuff: new Map<any, any>([
    [1, [2, 4, 5, 7, 2, 4]],
    ['blah', false],
    [{ a: 'b' }, { a: 'hi' }],
    [3, 4],
    ['somestring', 'anotherString']
  ]),
  tags: new Set(['a', 'b', 'dd'])
}));

const enc = encode(test, options);
const dec = decode(enc, options);

result:

I know set's are not supported out of the box, and will add my own extension for that, but this issue is blocking me now.
Is there a mistake in my code?