Strided structure topo crashes topology::length function.

[BradWhitlock]

I made a strided structured topo and wanted to compute its length using topology::length(). It crashes because the number of children (due to offsets, strides) causes the code to index out of bounds.

int
main()
{
    conduit::Node n;
    conduit::Node &coords = n["coordsets/coarse_coords"];
    coords["type"] = "explicit";
    coords["values/x"] = std::vector<double>{
        0., 1.,
        0., 1.,
        0., 1.,
        0., 1.,
        0., 1.,
        0., 1.,
        0., 1.};
    coords["values/y"] = std::vector<double>{
        0., 0.,
        1., 1.,
        2., 2.,
        3., 3.,
        4., 4.,
        5., 5.,
        6., 6.};

    conduit::Node &topo = n["topologies/coarse"];
    topo["type"] = "structured";
    topo["coordset"] = "coarse_coords";
    topo["elements/dims/i"] = 1;
    topo["elements/dims/j"] = 6;
    topo["elements/dims/k"] = 0;
    topo["elements/dims/offsets"] = std::vector<int>{2,2};
    topo["elements/dims/strides"] = std::vector<int>{1,5};

    n.print();

    conduit::Node info;
    bool ok = conduit::blueprint::mesh::verify(n, info);
    cout << "ok = " << ok << endl;
    info.print();

    // This crashes!
    auto len = conduit::blueprint::mesh::topology::length(topo);
    cout << "len = " << len << endl;
}

[BradWhitlock]

Working on a fix.