In alternativePathSearch method weighted_packed_paths is have empty paths if the middle node is also the starting node, so in debug mode there is an assertion and ub in release mode.

The issue can be reproduced with the OSM export https://www.openstreetmap.org/export#map=15/56.9103/14.5320, updated weights from crash.txt file and query curl 'http://localhost:5000/route/v1/driving/14.5303422%2C56.9087067%3B14.52962589263916%2C56.90761947631836.json?geometries=polyline&alternatives=true&steps=true&overview=full&annotations=true'

Values in the file are weights but not rates, so to reproduce the issue the line

        const auto weight = rate;