I am getting this error when I attempt to submit my answer. I passed the first test, but this is coming up for the second. I have no idea what the test is, so I'm not sure how to proceed with fixing my answer.

_stream_writable.js:171
 if (Buffer.isBuffer(chunk))
             ^
TypeError: Cannot call method 'isBuffer' of undefined
    at Socket.Writable.write (_stream_writable.js:171:14)
    at Socket.write (net.js:615:40)
    at Console.log (console.js:53:16)
    at 
    at Object.Test.handleError 
    at [eval]:3:6
    at Object. ([eval]-wrapper:6:22)
    at 
    at evalScript (node.js:536:25)
    at startup (node.js:80:7)