it is SIGILL (Illegal instruction), when I was solving the problem 797 on leetcode:Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n – 1, find all possible paths from node 0 to node n – 1 and return them in any order.

The graph is given as follows: graph[i] is a list of all nodes you can visit from node i (i.e., there is a directed edge from node i to node graph[i][j]).

I write the code like that:

bool DFS(vector<vector<int>>& graph,vector<vector<int>>&ans,vector<int>&path,int Node){
    if(Node==graph.size()-1){
        path.push_back(Node);
        ans.push_back(path);
        path.pop_back();
        return true;
    }
    for(auto posNode:graph[Node]){
        path.push_back(Node);
        if(!DFS(graph,ans,path,posNode)){
            path={-1};
            return false;
        }
    }
}
vector<vector<int>> allPathsSourceTarget(vector<vector<int>>& graph) {
    int Node=0;
    vector<vector<int>>ans;
    for(auto posNode:graph[Node]){
        vector<int>path;
        path.push_back(Node);
        if(DFS(graph,ans,path,posNode)){
            ans.push_back(path);
        }
    }
    return ans;

}

when the program goes to:for(auto posNode:graph[Node]) in DFS, it throws out a exception which is: SIGILL (Illegal instruction). why this accrued?