I can't figure out what's wrong with my code. I'm getting random integer output with the "{ }" input. I suspect it's some uninitialized value but I can't figure it out.

Thanks

```
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
struct Entry {
Entry(TreeNode* n, int prev) : node(n), prev_sum(prev) {}
TreeNode* node;
int prev_sum;
};
int sumNumbers(TreeNode *root) {
vector<Entry> entries;
entries.emplace_back(root, 0);
int total_sum = 0;
while (!entries.empty()) {
Entry current = entries.back();
entries.pop_back();
if (current.node == NULL) {
total_sum += current.prev_sum;
} else {
int current_sum = current.prev_sum + current.node->val;
entries.emplace_back(current.node->left, current_sum);
entries.emplace_back(current.node->right, current_sum);
}
}
}
};
```