#vulnerable code 
                                public void start() {
        List<Node> nodes = discoverHandler.getLocalNodes(network.maxOutCount());
        if (nodes == null && nodes.isEmpty()) {
            nodes = getSeedNodes();
        }
        for (Node node : nodes) {
            node.setType(Node.OUT);
            node.setStatus(Node.WAIT);
            addNodeToGroup(NetworkConstant.NETWORK_NODE_OUT_GROUP, node);
        }
        running = true;
        TaskManager.createAndRunThread(NulsConstant.MODULE_ID_NETWORK, "NetworkNodeManager", this);
        discoverHandler.start();
    } 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void start() {
        List<Node> nodes = discoverHandler.getLocalNodes(network.maxOutCount());
        if (nodes == null || nodes.isEmpty()) {
            nodes = getSeedNodes();
        }
        for (Node node : nodes) {
            node.setType(Node.OUT);
            node.setStatus(Node.WAIT);
            addNodeToGroup(NetworkConstant.NETWORK_NODE_OUT_GROUP, node);
        }
        running = true;
        TaskManager.createAndRunThread(NulsConstant.MODULE_ID_NETWORK, "NetworkNodeManager", this);
        discoverHandler.start();
    }