http status 412 on simple proxy/web server

[wa1gon]

I have written this simple proxy/static web server that first checks to see if a local copy exist, if not then it proxy to an application server.

It is a simple GET request with no query strings.

Here is the guts of the code:

server.createServer((req: Request, res: any) => {

  let fileName = isFileLocal(req.url);

  if (fileName) {

    fs.readFile(fileName, "binary", function (err: string, file: any) {
      if (err) {
        res.writeHead(500, { "Content-Type": "text/plain" });
        res.write(err + "\n");
        res.end();
        return;
      } else {

        res.writeHead(200, { "Cache-Control": "no-cache, no-store, must-revalidate" });
        res.write(file, "binary");
        res.end();
      }
    });
  } else {
    console.log("Proxying Request: %s", hostname + req.url);
    console.log(req.headers)
    proxy.web(req, res, { target: hostname + req.url });
    // res.writeHead(200, { 'Content-Type': 'text/plain' });
    // res.write('Request successfully proxies!' + '\n' + JSON.stringify(req.headers));
    // res.end();
  }
}).listen(port);

Suggestions on what I am doing wrong?