Dr Memory crash in Visual Studio with "WARNING: application exited with abnormal code 0xc0000409"

Question

I made a Node class and tried to implement a simple tree structure using C++. I tested the code, visual studio was able to compile and output the expected results. However, when I tried Dr Memory to check memory leak, Dr Memory always crash at certain points, including: 1) in the Node class constructor "col = vec[0].size()" 2) in the distance function "col = vec[0].size()"

If I kept those lines, visual studio can compile and output the right thing, however, Dr Memory crash... If I commented those lines, Dr Memory works... So I am quite confused what part went wrong, is the nodes on the heap? or the vector? or Dr Memory... Thank you

// node class
class Node {
public:
    vector<vector<int>> board;
    int row;
    int col;
    Node(vector<vector<int>> &vec): board(vec) {
        row = vec.size();
        col = vec[0].size();
    }
    Node(Node *&node): board(node->board) {}
};

// calculate distance
int distance(v2_i &vec) {
    int ans = 0;
    int row = vec.size();
    int col = vec[0].size();
    for(int i=0; i<row; i++) {
        for(int j=0; j<col; j++) ans += abs(vec[i][j]-(i*row+j+1));
    }
    return ans;
}

// main function
int main() {
    vector<vector<int>> startBoard = input_txt();
    Node *node_1 = new Node(startBoard);
    Node *node_2 = new Node(node_1);

    cout << distance(node_2->board) << endl;

    delete node_1;
    delete node_2;
    return EXIT_SUCCESS;
}