bitcoinjs – Create Bitcoin Transaction: Need validator function to validate signatures

I am trying to send the bitcoin with my private key using the script and the bitcoinjs-lib. I am constantly getting the error Need validator function to validate signatures over the line when I call const isValid = psbt.validateSignaturesOfAllInputs();.

I am not able to figure out how to resolve this,

const ecc = require('tiny-secp256k1');
const ECPairFactory = require('ecpair').default;
const ECPair = ECPairFactory(ecc);
const axios = require('axios');

const NETWORK = bitcoin.networks.testnet
// const network = bitcoin.networks.testnet; // Or bitcoin.networks.bitcoin for mainnet
const sender_address = "tb1qmrhvnv0w6p9asunmsua3ua829artanps6jfza7"; // Replace with your address
const PRIVATE_KEY_WIF = "PRIVATE_KEY"; 
const DESTINATION_ADDRESS = "mggvPKgz8UJu6sWWdxwPKLKYoyHKhJGzCY"; 
const FEE = 1000; 

async function sendBitcoin() {
    try {
        // Import private key
        const keyPair = ECPair.fromWIF(PRIVATE_KEY_WIF, NETWORK);

        // Generate the address (Native SegWit - P2WPKH)
        const { address } = bitcoin.payments.p2wpkh({
            pubkey: Buffer.from(keyPair.publicKey),
            network: NETWORK,
        });
        console.log(`Sending from: ${address}`);

        // Fetch UTXOs for the address
        const utxos = await getUtxos();
        console.log(`Fetched UTXOs:`, utxos);

        if (!Array.isArray(utxos) || utxos.length === 0) {
            throw new Error("No UTXOs available for the given address.");
        }

        // Create a new PSBT
        const psbt = new bitcoin.Psbt({ network: NETWORK });
        console.log(`Initialized PSBT:`, psbt);

        let totalInput = 0;

        // Add inputs from UTXOs
        utxos.forEach((utxo) => {
            console.log(`Adding UTXO: ${JSON.stringify(utxo)}`);
            psbt.addInput({
                hash: utxo.txid,
                index: utxo.vout,
                witnessUtxo: {
                    script: Buffer.from(bitcoin.address.toOutputScript(address, NETWORK)),
                    value: utxo.value,
                },
            });
            totalInput += utxo.value;
        });

        // Calculate the amount to send
        const sendAmount = 2000;
        if (sendAmount <= 0) {
            throw new Error("Insufficient funds after deducting fees.");
        }

        // Add output for destination
        psbt.addOutput({
            address: DESTINATION_ADDRESS,
            value: sendAmount,
        });

        // Add change output if applicable
        const change = totalInput - sendAmount - FEE;
        if (change > 0) {
            const changeAddress = bitcoin.payments.p2wpkh({
                pubkey: Buffer.from(keyPair.publicKey),
                network: NETWORK,
            }).address;
            console.log(`Adding change output: ${changeAddress}`);
            psbt.addOutput({
                address: changeAddress,
                value: change,
            });
        }

        utxos.forEach((_, index) => {
          psbt.signInput(index, {
              publicKey: Buffer.from(keyPair.publicKey),
              sign: (hash) => {
                  const signature = keyPair.sign(hash);
                  return Buffer.from(signature); 
              },
          });
      });

      console.log(`Signed all inputs`);

        const isValid = psbt.validateSignaturesOfAllInputs();
        console.log(`Signatures valid: ${isValid}`);

        psbt.finalizeAllInputs();

        const rawTransaction = psbt.extractTransaction().toHex();
        console.log(`Raw Transaction: ${rawTransaction}`);

        let myHeaders = new Headers();
        myHeaders.append("Content-Type", "application/json");

        let raw = JSON.stringify({
            "method": "sendrawtransaction",
            "params": [
              rawTransaction
            ]
        });

        let requestOptions = {
            method: 'POST',
            headers: myHeaders,
            body: raw,
            redirect: 'follow'
        };

        let quickNodeUrl = "https://abcd-efgh-igkl.btc-testnet.quiknode.pro/6a1xxxxxxxxxxxxxxxxxxxxxxxxx4/";

        fetch(quickNodeUrl, requestOptions)
            .then(response => response.json())
            .then(result => {
                console.log("Broadcast Response: ", result);
            })
            .catch(error => console.log('Error broadcasting transaction:', error));

    } catch (error) {
        console.error(`Error: ${error.stack}`);
    }
}

sendBitcoin();

async function getUtxos() {
    try {
        const response = await axios.get(`https://blockstream.info/testnet/api/address/${sender_address}/utxo`);
        return response.data;
    } catch (error) {
        console.error(`Error fetching UTXOs: ${error.message}`);
        return [];
    }
  } ```.   
Stack Trace Error:
``` Error: Need validator function to validate signatures
    at Psbt._validateSignaturesOfInput (/Users/harshkushwah/Desktop/Btc_Tx_Listener/node_modules/bitcoinjs-lib/src/psbt.js:424:13)
    at Psbt.validateSignaturesOfInput (/Users/harshkushwah/Desktop/Btc_Tx_Listener/node_modules/bitcoinjs-lib/src/psbt.js:416:17)
    at /Users/harshkushwah/Desktop/Btc_Tx_Listener/node_modules/bitcoinjs-lib/src/psbt.js:404:12
    at Array.map ()
    at Psbt.validateSignaturesOfAllInputs (/Users/harshkushwah/Desktop/Btc_Tx_Listener/node_modules/bitcoinjs-lib/src/psbt.js:403:52)
    at sendBitcoin (/Users/harshkushwah/Desktop/Btc_Tx_Listener/transfer-seqWit.js:93:30)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5) ```