Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/4804
Valid neighbor indexes are in the range of [0, ntotal). Fix range check in
NSG::search_on_graph() that accepted an index value of ntotal.
NOTE: This data structure uses -1 as a termninal sentinal. The call to
nsg::Graph::get_neighgbors() above the for loop that includes the upper bound
check stops when encountering a negative index. This means the check for
negative values has already occurred and does not need to be repeated inside
the loop.
Reviewed By: junjieqi, sh00s
Differential Revision: D93040548
fbshipit-source-id: e1bde990a459c86dfaebdd2f780375b7922fc5f5
