Segmentation fault when getting route

Hello
I've built valhalla tiles for a whole country and extracted graphs for a specific bounding box (for a city) using the python script in the documents (https://valhalla.readthedocs.io/en/latest/tiles/). But when I get routes near city edges, Valhalla crashes with signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0xc

This is the stack trace:

```
(valhalla::baldr::GraphTile::node(unsigned int) const+24)
valhalla::baldr::GraphTile::node(unsigned int) const
/Valhalla/valhalla/valhalla/baldr/graphtile.h:150:15
(valhalla::baldr::GraphTile::GetOpposingEdgeId(valhalla::baldr::DirectedEdge const*) const+30)
valhalla::baldr::GraphTile::GetOpposingEdgeId(valhalla::baldr::DirectedEdge const*) const
/Valhalla/valhalla/valhalla/baldr/graphtile.h:230:48
(valhalla::thor::BidirectionalAStar::ExpandReverseInner(valhalla::baldr::GraphReader&, valhalla::sif::BDEdgeLabel const&, valhalla::baldr::DirectedEdge const*, valhalla::baldr::NodeInfo const*, unsigned int, valhalla::thor::EdgeMetadata const&, unsigned int&, valhalla::baldr::GraphTile const*)+184)
valhalla::thor::BidirectionalAStar::ExpandReverseInner(valhalla::baldr::GraphReader&, valhalla::sif::BDEdgeLabel const&, valhalla::baldr::DirectedEdge const*, valhalla::baldr::NodeInfo const*, unsigned int, valhalla::thor::EdgeMetadata const&, unsigned int&, valhalla::baldr::GraphTile const*)
/Valhalla/valhalla/src/thor/bidirectional_astar.cc:440:29
(valhalla::thor::BidirectionalAStar::ExpandReverse(valhalla::baldr::GraphReader&, valhalla::baldr::GraphId const&, valhalla::sif::BDEdgeLabel&, unsigned int, valhalla::baldr::DirectedEdge const*, bool)+182)
valhalla::thor::BidirectionalAStar::ExpandReverse(valhalla::baldr::GraphReader&, valhalla::baldr::GraphId const&, valhalla::sif::BDEdgeLabel&, unsigned int, valhalla::baldr::DirectedEdge const*, bool)
/Valhalla/valhalla/src/thor/bidirectional_astar.cc:349:22
(valhalla::thor::BidirectionalAStar::GetBestPath(valhalla::Location&, valhalla::Location&, valhalla::baldr::GraphReader&, std::__ndk1::shared_ptr const*, valhalla::sif::TravelMode, valhalla::Options const&)+832)
valhalla::thor::BidirectionalAStar::GetBestPath(valhalla::Location&, valhalla::Location&, valhalla::baldr::GraphReader&, std::__ndk1::shared_ptr const*, valhalla::sif::TravelMode, valhalla::Options const&)
/Valhalla/valhalla/src/thor/bidirectional_astar.cc:649:7
(valhalla::thor::thor_worker_t::get_path(valhalla::thor::PathAlgorithm*, valhalla::Location&, valhalla::Location&, std::__ndk1::basic_string, std::__ndk1::allocator> const&, valhalla::Options const&)+118)
valhalla::thor::thor_worker_t::get_path(valhalla::thor::PathAlgorithm*, valhalla::Location&, valhalla::Location&, std::__ndk1::basic_string, std::__ndk1::allocator > const&, valhalla::Options const&)
/Valhalla/valhalla/src/thor/route_action.cc:330:32
(valhalla::thor::thor_worker_t::path_depart_at(valhalla::Api&, std::__ndk1::basic_string, std::__ndk1::allocator> const&)+310)
valhalla::thor::thor_worker_t::path_depart_at(valhalla::Api&, std::__ndk1::basic_string, std::__ndk1::allocator > const&)
/Valhalla/valhalla/src/thor/route_action.cc:496:23
(valhalla::thor::thor_worker_t::route(valhalla::Api&)+92)
valhalla::thor::thor_worker_t::route(valhalla::Api&)
/Valhalla/valhalla/src/thor/route_action.cc:258:5
(valhalla::tyr::actor_t::route(std::__ndk1::basic_string, std::__ndk1::allocator> const&, std::__ndk1::function const&)+72)
valhalla::tyr::actor_t::route(std::__ndk1::basic_string, std::__ndk1::allocator > const&, std::__ndk1::function const&)
/Valhalla/valhalla/src/tyr/actor.cc:55:22
```

Is there any bug in the python script and some graphs are missing? (also I should mention that some of the graphs returned from the python script does not exist in the valhalla_tiles output directory)