Bug Report for lru-cache

[javalip]

Bug Report for https://neetcode.io/problems/lru-cache

Please describe the bug below and include any steps to reproduce the bug or screenshots if possible.
I have a working solution for LRU cache from leetcode. However here in neetcode its giving NPE. Below is the code for LRU cache.
class LRUCache {
class Node{
int key;
int val;
Node next;
Node prev;
Node(int key, int value){
this.key=key;
this.val=value;
}
}

int capacity;
HashMap<Integer, Node> map;
Node head;
Node tail;
public LRUCache(int capacity){
    this.capacity = capacity;
    map = new HashMap<>();
    head = new Node(-1,-1);
    tail = new Node(-1,-1);
    head.next=tail;
    tail.prev=head; 
}
private void removeNode(Node node){
    node.prev.next =node.next;
    node.prev=head;
    node.next.prev = node;
    head.next=node;
}
private void addToHead(Node node){
    node.next=head.next;
    head.next.prev=node;
}


public int get(int key) {
    if(map.containsKey(key)){
         //remove node
          // add to head
            //return value
    Node curr = map.get(key);
    removeNode(curr);   
    addToHead(curr);
    return curr.val;
    } else {
        return -1;
    }       
}

public void put(int key, int value) {
    // if key already exists
    //remove from linked list
    //add to head,
    //update value.
    if (map.containsKey(key)){
        //remove as its most recently used now.
        Node node = map.get(key);
        removeNode(node);
        //add to head
        addToHead(node);
        node.val=value;
    }else{
        if(map.size()==capacity){
            // remove LRU
            Node tailPrev = tail.prev;
            removeNode(tailPrev);
            //remove from map.
            map.remove(tailPrev.key);
        }
        Node newNode = new Node(key,value);
        map.put(key,newNode);
        //add to head
        addToHead(newNode);
    }     
}

}