Expression: map/set iterator not dereferencable in RegionGenerator

[s7jones]

In RegionGenerator, the code:

std::map<nodeID, Chokepoint*> node2chokepoint;
for (const auto& chokeNodeId : graph.chokeNodes) {
	auto it = graph.adjacencyList[chokeNodeId].begin();
	Region* r1 = node2region[*it];
	++it;
	Region* r2 = node2region[*it];
	BWAPI::Position side1(chokepointSides.at(chokeNodeId).side1);
	BWAPI::Position side2(chokepointSides.at(chokeNodeId).side2);
	Chokepoint* newChokepoint = new ChokepointImpl(std::make_pair(r1, r2), std::make_pair(side1, side2));
	chokepoints.insert(newChokepoint);
	node2chokepoint.insert(std::make_pair(chokeNodeId, newChokepoint));
}

throws an error Expression: map/set iterator not dereferencable at Region* r2 = node2region[*it];.

This is for map with the resulting hash:
+ filename "bwapi-data/BWTA2/d2f5633cc4bb0fca13cd1250729d5530c82c7451.bwta" std::basic_string<char,std::char_traits<char>,std::allocator<char> >

in TerrainAnalysis::analyze().