HashTable Implementation Get and Set Operator Overloading

I'm trying to implement a basic hashtable. I'm using a LinkedList to resolve collisions.

My get and set methods are giving me a bunch of trouble, and I'm not really sure what the issue is. I believe I'm overloading the operator's correctly, and I think my LinkedList append functionality is broken.

class HashTable {
  struct Node{
    int key;
    int value;
    Node *next;
  };
  Node **table;
  int hash_func(int key) const {
    return key % TABLE_SIZE;
  }
public:
  HashTable() {
    table = new Node*[TABLE_SIZE]();
    for (int i = 0; i < TABLE_SIZE; ++i)
      table[i] = nullptr;
  }

  int& operator[](int const key) {
    int h_key = hash_func(key);

    while(table[h_key]) {
      table[h_key] = table[h_key]->next;
    }

    table[h_key] = new Node;
    table[h_key]->key = key;
    table[h_key]->next = table[h_key];

    return table[h_key]->value;
  }

  int operator[](int const key) const {
    int h_key = hash_func(key);

    while (table[h_key]) {
      if (table[h_key]->key == key) {
        return table[h_key]->value;
      }
      table[h_key] = table[h_key]->next;
    }
    return 0;
  }
};