无法初始化内部类的对象C++

我有两个类，一个嵌套在另一个里面:

class List {
private:
    class Node {
    public:
        Token data;
        Node* next;
        Node(const Token &dataItem, Node* nextptr);
    };
    Node* first;
    int length;
public:
    List();
    virtual ~List();
    void insert (const Token &t);
    Node* lookup(const Token &t) const;  
};

类节点有它的构造函数:

List::Node::Node(const Token &dataItem, Node* nextptr): data(dataItem) {
        data = dataItem;
        next = nextptr;
    }

但是当我尝试在插入方法中初始化一个节点时，像这样:

void List::insert (const Token &t){
if(first == NULL){
Node* node = new Node(t, nullptr); //PROGRAM DIES HERE
first = node;
cout<<"hey"<<endl;
}else{
    Node* isHere = lookup(t);
    //if not
    if(isHere == NULL){
        Node* temp = first;
                Node* node = new Node(t, NULL);
                while(true){
                    if((temp->data.getName().compare(t.getName())>0)or(temp->next==NULL)){
                        Node* temp2 = temp->next;
                        temp->next = node;
                        node->next = temp2;
                        break;
                    }
                    temp=temp->next;
                }
    }
    //if node exists
    else{
        cout<<"node exists"<<endl;
        isHere->data.newEntry(t.getLines()[0]);
        cout<<"node out"<<endl;
    }
  }
}

查找方法:

List::Node* List::lookup(const Token &t) const{
    if(first == NULL)
        return first;
    if(first->data.isEquivalent(t))
                   return first;
       cout<<"finished coparre"<<endl;
    Node* temp = first;
       while(temp->next != NULL){
           cout<<"in da loop"<<endl;
           temp = temp->next;
           if(temp->data.isEquivalent(t))
               return temp;
       }
       return NULL;
}

程序只是在我注释的行处静默死亡。我在这里做错了什么?好的，这是代币。我不认为那里有问题，但它也被要求，所以这里是来源:令牌头:

class Token {
    std::string name; // token name
    int frequency;//frequency
    Vector lines;//lines where the token is present
public:
    //explanations for the methods in the Token.cpp
    Token(std::string tokenname, int linenumber);
    virtual ~Token();
    void newEntry(int &linenumber);
    Vector getLines() const;
    std::string getName() const;
    int getFrequency() const;
    const bool isEquivalent(const Token &t);    

;

标记方法:

Token::Token(string tokenname, int linenumber) {
    // TODO Auto-generated constructor stub
    name = tokenname;
    frequency=1;
    lines.push_back(linenumber);
}
void Token::newEntry(int &linenumber){
    cout<< "enter new entry"<<endl;
    frequency++;
    lines.push_back(linenumber);
    cout<< "finish  new entry"<<endl;
}
std::string Token::getName() const{
    return name;
}
const bool Token::isEquivalent(const Token &t){
    if(t.getName().compare(name)==0)
    return true;
    else
        return false;
}
Vector Token::getLines() const{
    return lines;
}