Why am I getting write after end error when running the code on my computer?

So, I followed along with the video, but when I run the code on my local machine, I keep getting "write after end" errors when I jump between different requests.

For example,

1. Started the server
2. Requested "/" --> the page showed up
3. Requested "/chalkers" --> I saw a line saying "chalkers has x # of badges"
4. Requested "zackmccartney2" (my username) --> server crashed;

And by crashed I mean: got an error in Chrome saying "localhost refused to connect"

In my console, I got this error: " events.js:141 throw er; // Unhandled 'error' event ^

Error: write after end at ServerResponse.OutgoingMessage.write (_http_outgoing.js:430:15) at Profile.<anonymous> (/Users/Zack/Desktop/Build a Simple Dynamic Site with Node.JS/stage_2_video_2/router.js:46:16) at emitOne (events.js:77:13) at Profile.emit (events.js:169:7) at ClientRequest.<anonymous> (/Users/Zack/Desktop/Build a Simple Dynamic Site with Node.JS/stage_2_video_2/profile.js:24:28) at ClientRequest.g (events.js:260:16) at emitOne (events.js:77:13) at ClientRequest.emit (events.js:169:7) at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:419:21) at HTTPParser.parserOnHeadersComplete (_http_common.js:103:23) "

I checked my code; everything seems to be ok (of course, seems is the operative word) I've restarted the server and run through this a few more times. I keep getting this error, but not in the same sequence. Sometimes, I can request a bunch of pages in a row before it cops out. Sometimes, only 2.

Does anyone have any idea why I keep receiving this error?

Thanks! Zack