Edge Case: Mistake on isolating Map entries

[lxsmnsyc]

const a = {
  d: {},
  map: new Map,
  b: {
    c: {
      foo: 'bar'
    }
  }
};

a.map.set(a, a.b.c);

a.b.c.parent = a.b;
a.b.c.d = a.d;

This causes a.b.c to be undefined because the origin reference, located at a.map, is deferred due to recursion.