deleteValue not working properly

[lxb007981]

RBTree rbTree1;
rbTree1.insertValue(1);
rbTree1.insertValue(2);
rbTree1.inorder();//output 1, 2
rbTree1.deleteValue(1);
rbTree1.inorder();//output nothing

[mingyuanlee]

The impl is not correct, here we set the root to null in fixDeleteTree:

if (node == root) {
    root = nullptr;
    return;
  }