New turf union returns a strange Polygon.

I am trying to unite two polygons. First https://gist.github.com/ilijaz/e4fc41abb6e12fe9f346434a06d948db Second https://gist.github.com/ilijaz/c7fb49ad134173ce6b502dbcc449ffa9 Also first polygon created after union of some as second polygons.

const union = require('@turf/union').default;
const turf = require('@turf/turf');

const first = {"..."};
const second = {"..."};
const un1 = union(first, second);
console.log(turf.area(un1), turf.area(first), turf.area(second))

I’ve had https://gist.github.com/ilijaz/51b426f9131ab29141bf2a6660e6ad77 as result. You can see it’s wrong.

1334311.8920525517 20866.04727530979 268.7401291002204

Is it problem of tolerance? Is it normal that polygon has LinearRings that do not form a closed LlineString. They have only two coordinates.

Opposite of this case, union function from turf/turf works fine for me but it’s about 2 times slowly. Here result on same input data https://gist.github.com/ilijaz/78997225ea130a0a1db1b40990f90237

[rowanwins]

Resolved since v6.2.0

[EvertEt]

Indeed. The bug is that here the algorithm assumes multiple polygons are separate but in this case they should not be split up as the second one is a hole in the first one. https://github.com/Turfjs/turf/blob/a371807f78364820f15ab8f9ee3dc5aba51b7bac/packages/turf-union/index.ts#L47