for (unsigned int i = 0; i < vector_active (node->from); i++)
{
adj = vector_slot (node->from, i);
+ if (!adj) continue;
for (unsigned int j = 0; j < vector_active (adj->to); j++)
if (vector_slot (adj->to, j) == node)
vector_unset (adj->to, j);
for (unsigned int i = 0; i < vector_active (node->to); i++)
{
adj = vector_slot (node->to, i);
+ if (!adj) continue;
for (unsigned int j = 0; j < vector_active (adj->from); j++)
if (vector_slot (adj->from, j) == node)
vector_unset (adj->from, j);