Graph<T>::removeNode has potential to throw due to optional being accessed early #418
Description
The implementation that added isolated nodes seems to be assuming that nodeOpt will always have a value. This is untrue if the node does not exist:
template <typename T>
void Graph<T>::removeNode(const std::string &nodeUserId) {
auto nodeOpt = getNode(nodeUserId);
auto isolatedNodeIt = isolatedNodesSet.find(nodeOpt.value());
...
nodeOpt.value() is called before verifying the optional has something in it.
This should be updated to something like this:
template <typename T>
void Graph<T>::removeNode(const std::string &nodeUserId) {
auto nodeOpt = getNode(nodeUserId);
auto isolatedNodeIt = isolatedNodesSet.end();
if (nodeOpt) {
isolatedNodeIt = isolatedNodeIt.find(nodeOpt.value());
}
...
The tests should also be updated to test the case where we try to remove a node that does not exist in the graph.