[BUG] some polygon features are generated with invalid geometries

[spwoodcock]

Describe the bug

I have a bunch of building polygons from a data extract:

Running the QGIS 'Check validity' algorithm, I identify 7 invalid geoms:

The errors are identified as IGNORE_RING_SELF_INTERSECTION. You can see the self-intersection here:

Running the QGIS 'Fix geometries' algorithm, we can remove the self- intersection automatically:

Expected behavior

Now I'm not sure if this 'invalid' geoms are the result of:

1. raw-data-api taking the OSM nodes as they are (so the geom accurately reflects the error produced by the user). In which case, not solvable.
2. Something going wrong in the OSM XML --> geometry conversion process, resulting in errors such as self-intersecting polygons.

My assumption is it's probably (1), but I thought I would document this just in case.

The data extract to reproduce this:

283_map_features.geojson.txt