I had a "complex" polygon that i wanted to know if a certain point was in it, but it looks like the boundary.safeSortedClockwise() at the init of the Polygon data class isn't working correctly. I hadn't time to validate why, but here is the polygon before and after the safeSortedClockwise algorithm.

Here is the problematic geojson file: https://pastebin.com/bnAm54DV
Thank you! And keep the good work!