Imported checksum file from github link provided on their website

ERROR SHOWN

TypeError [ERR_INVALID_ARG_TYPE]: The "data" argument must be of type string or an instance of Buffer, TypedArray, or DataView. Received undefined at new NodeError (node:internal/errors:372:5) at Decipheriv.update (node:internal/crypto/cipher:176:11) at Function.decrypt (D:\MERN-STACK\server\paytm\PaytmChecksum.js:15:28) at Function.verifySignatureByString (D:\MERN-STACK\server\paytm\PaytmChecksum.js:56:34) at Function.verifySignature (D:\MERN-STACK\server\paytm\PaytmChecksum.js:47:24) at paytmResponse (file:///D:/MERN-STACK/server/controller/payment-controller.js:27:41) at Layer.handle [as handle_request] (D:\MERN-STACK\server\node_modules\express\lib\router\layer.js:95:5) at next (D:\MERN-STACK\server\node_modules\express\lib\router\route.js:144:13) at Route.dispatch (D:\MERN-STACK\server\node_modules\express\lib\router\route.js:114:3) at Layer.handle [as handle_request] (D:\MERN-STACK\server\node_modules\express\lib\router\layer.js:95:5)

/THIS IS THE CODE FOR RESPONSE PART/

export const paytmResponse=(request,response)=>{
    const form=new formidable.IncomingForm();
    let paytmCheckSum=request.body.CHECKSUMHASH;
    delete request.body.CHECKSUMHASH;

    let isVerifySignature=paytmchecksum.verifySignature(request.body,paytmMerchantKey,paytmCheckSum);

    if(isVerifySignature){
        let paytmParams={};
        paytmParams['MID']=request.body.MID;
        paytmParams['ORDERID']=request.body.ORDERID;

        paytmchecksum.generateSignature(paytmParams,paytmMerchantKey).then(function(checksum){
            paytmParams['CHECKSUMHASH']=checksum;

            let post_data=JSON.stringify(paytmParams);

            let options={
                hostname:'securegw-stage.paytm.in',
                port:443,
                path:'/order/status',
                headers:{
                    'Content-Type':'application/json',
                    'Content-Length':post_data.length 
                }
            }

            let res="";
            let post_req=https.request(options,function(post_res){
                post_res.on('data',function(chunk){
                    res +=chunk;
                });

                post_req.on('end',function(){
                    let result=JSON.parse(res)
                    response.redirect('http://localhost:3000/')
                })
            });

            post_req.write(post_data);
            post_req.end();
        })
    }else{
        console.log('Checksum mismatched');
    }
}