BLOCK_TYPE_IS_VALID(pHead->nBlockUse) occurs on main return

template <class type>
class List{
    public:
        List<type>::List(){
            _list = new type[10];
        }
        List<type>::~List(){
            delete this->_list;
        }       

    private:
        type* _list;

};

in main:

int main(){
List<std::string> l = List<std::string>();

return 0;

}

It happens only if I put non primitive variable in <> and dont use new.

I can avoid this by doing it like this: List<string> *l = new List<string>();

What I'am missing? In my mind it should perfectly fine.