ReactJS - Bugs con el CORS

//Tengo problemas. me dice que hay bug, pero no logro saber donde podría ser.

'use strict';

module.exports.multiplyRange = (event, context, callback) => {

var start = event.start;
var end = event.end;

// Fix code below
var range = [];
for (var i = start; i <= end; i++) {
range[] = range.push(i);
}

let multiply = (a, b) => a + b;
var result = l.reduce(m);

const response = {
statusCode: 200,
method: POST,
endpoint: multiply-range,
headers: {
'Access-Control-Allow-Origin': '*', // Required for CORS support to work
},
body: {
result: result,
},
};
callback(null, response);
};

Esto es Node?