Segmentation fault when calling findArc

[didif]

Found in version: 1.3.1

The call to findArc in the bellow program yields segmentation fault on Ubuntu 16.04:

int main() {

ListGraph? g; ListGraph::Node n = g.addNode(); ListGraph::Arc a = findArc(g, INVALID, n); return 0;

}

I expect to get INVALID back from findArc in this case.

[Alpar Juttner]

It is not a bug. It makes no sense to find arcs between INVALID and a node. The second and third parameters must be valid nodes.

This kind of assumption is there basically everywhere in LEMON. For example, g.source(INVALID) will also cause troubles.