引发了异常: 读取访问权限冲突。 this 是 nullptr。

求指点，谢谢。

调试tetgen库时遇到问题

问题代码：

//// 头文件
class memorypool {

  public:

    void **firstblock, **nowblock;
    void *nextitem;
    void *deaditemstack;
    void **pathblock;
    void *pathitem;
    int  alignbytes;
    int  itembytes, itemwords;
    int  itemsperblock;
    long items, maxitems;
    int  unallocateditems;
    int  pathitemsleft;

    memorypool();
    memorypool(int, int, int, int);
    ~memorypool();
    
    void poolinit(int, int, int, int);
    void restart();
    void *alloc();
    void dealloc(void*);
    void traversalinit();
    void *traverse();
  };  

//// 函数
void tetgenmesh::memorypool::traversalinit()
{
  uintptr_t alignptr;
  // Begin the traversal in the first block.
  pathblock = firstblock;
  // Find the first item in the block.  Increment by the size of (void *).
  alignptr = (uintptr_t) (pathblock + 1);
  // Align with item on an `alignbytes'-byte boundary.
  pathitem = (void *)
    (alignptr + (uintptr_t) alignbytes -
     (alignptr % (uintptr_t) alignbytes));
  // Set the number of items left in the current block.
  pathitemsleft = itemsperblock;
}

//// 调用
void createtet()
{
    // 将点数据输入文件结构
    tetgenio in, out;

    // 创建 4 个节点的点数据
    int num_points = 4;
    double* points = new double[num_points * 3];

    // 设置节点坐标（这里假设节点坐标已知）
    points[0] = 0.0;
    points[1] = 0.0;
    points[2] = 0.0;
    points[3] = 1.0;
    points[4] = 0.0;
    points[5] = 0.0;
    points[6] = 0.0;
    points[7] = 1.0;
    points[8] = 0.0;
    points[9] = 0.0;
    points[10] = 0.0;
    points[11] = 1.0;

    // 将点数据赋值给 tetgenio 对象
    in.numberofpoints = num_points;
    in.pointlist = points;

    // 设置TETGEN现象和标志
    // 创建一个TetGen选项对象
    tetgenbehavior behavior;
    // 设置选项和标志
    behavior.quality = 1; // 设置质量约束
    behavior.minratio = 1.2; // 设置最小质量比率
    behavior.coarsen = 0; // 关闭网格简化

    // 调用TETGEN进行四面体化
    tetrahedralize(&behavior, &in, &out);
}

traversalinit函数报错，你到是把相关代码放出来呀
你放出来的代码里traversalinit函数根本都没有调用