get_leaves appends random points

hi! thanks for the great geolibs in rust which i'm currently porting my js app into.

i've encountered that get_leaves appends points from completely alien clusters. This happens only when the observed cluster can unroll into several nested clusters. At the max-zoom level it appends points fine.
Look like data indexes get messed up. Would be greatfull for any thoughts how to fix this

supercluster-rs / js demo:

btw, the porting of map/reduce from supercluster-js is also a cool feature to have: https://github.com/developmentseed/supercluster-rs/pull/13#issuecomment-2266354666