Why am I not able to insert elements into my linked-list implementation?

I am doing linkedlist implementation in java. Particularly, while doing insert operation, if the given index is more than the length of the linkedlist, I have to append the value to the linkedlist. Though I have written code for the same, it is not happening that way.

In order to debug this, I added lines for printing linkedlist. I could print the list just before the condition if(index >= this.length()) in the insert function but not able to print the linkedlist in the line inside the condition.

package com.learning.algorithms.LinkedList;

public class Node {
	int data;
	Node next;

	public Node() {
	}

	public Node(int i) {
		this.data = i;
		this.next = null;
	}
}

package com.learning.algorithms.LinkedList;

public class LinkedList {
	Node head;
	Node tail;

	public LinkedList() {
		this.head = new Node();
		this.tail = this.head;
	}

	public LinkedList(int value) {
		this.head = new Node();
		this.head.data = value;
		this.head.next = null;
		this.tail = this.head;
	}
	
	public LinkedList append(int value) {
		Node newNode = new Node(value);
		this.tail.next = newNode;
		this.tail = newNode;
		
		return this;
	}
	
	public void printList()	{
		Node useNode = this.head;
		
		while(useNode!=null)
		{
			System.out.println(useNode.data);
			useNode = useNode.next;
		}
		
		//print(useNode);
	}

	private void print(Node useNode) {
		if(useNode!=null)
		{
			System.out.println(useNode.data);
			print(useNode.next);
		}		
	}

	public LinkedList prepend(int i) {
		Node newNode = new Node(i);
		newNode.next = this.head;
		this.head  = newNode;
		return this;
	}

	public LinkedList insert(int index, int value) {
		if(index == 0)
		{
			this.prepend(value);
			return this;
		}
		
		this.printList();
		if(index >= this.length())
		{
			System.out.println("inside");
			this.printList();
			this.append(value);
			return this;
		}

		Node nodeJustBeforeGivenIndex = this.head;
		
		// getting node just before given index using while loop
		while(index>1)
		{
			nodeJustBeforeGivenIndex = nodeJustBeforeGivenIndex.next;
			index--;
		}
		
		// make an insert
		Node newNode = new Node(value);
		newNode.next = nodeJustBeforeGivenIndex.next;
		nodeJustBeforeGivenIndex.next = newNode;
		
		return this;
	}

	private int length() {
		int counnt = 0;
		
		if(this.head !=null ) {
			while(this.head !=null )
			{
				this.head = this.head.next;
				counnt++;
			}
		}
		
		return counnt;
	}
}

package com.learning.algorithms.LinkedList;

public class LinkedListImplementation {
	public static void main(String[] args)
	{
		LinkedList list = new LinkedList(10);
		
		list.append(5);
		list.append(16);
		list.prepend(1);
		list.insert(0, 15);
		list.insert(10, 222);
		
		list.printList();
	}
}

Console output for running this implementation class:

15
1
10
5
16
inside

You should not modify the head value inside the length method.

This will fix it:

private int length() {
    int counnt = 0;

    Node iter = this.head;
    while(iter !=null )
    {
    	iter = iter.next;
        counnt++;
    }
    
    return counnt;
}

Commenting just the two print stamtents inside insert, the output gets to be:

inside
15
1
10
5
16
222