JSON parsing issue on FCC 's verification process

Tell us what’s happening:
When applying the unit test for this lesson, my repl.it server fails with what appears to be a server side error originating at FCC’s verification process. In my repl.it console I can see the request come in and an error is generated.

Repl.it console error:

npm start

fcc-learn-node-with-express@0.1.0 start /home/runner/FCC-express-lessons
node server.js

Node is listening on port 3000…
*
GET / - ::ffff:172.18.0.1
*
SyntaxError: Unexpected token < in JSON at position 0
at JSON.parse ()
at /home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:91:26
at IncomingMessage. (/home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:33:7)
at IncomingMessage.emit (events.js:315:20)
at IncomingMessage.Readable.read (_stream_readable.js:505:10)
at flow (stream_readable.js:1005:34)
at resume
(_stream_readable.js:986:3)
at processTicksAndRejections (internal/process/task_queues.js:84:21)
SyntaxError: Unexpected token < in JSON at position 0
at JSON.parse ()
at /home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:99:28
at IncomingMessage. (/home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:33:7)
at IncomingMessage.emit (events.js:315:20)
at IncomingMessage.Readable.read (_stream_readable.js:505:10)
at flow (stream_readable.js:1005:34)
at resume
(_stream_readable.js:986:3)
at processTicksAndRejections (internal/process/task_queues.js:84:21)
_http_outgoing.js:518
throw new ERR_HTTP_HEADERS_SENT(‘set’);
^

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:518:11)
at ServerResponse.header (/home/runner/FCC-express-lessons/node_modules/express/lib/response.js:771:10)
at ServerResponse.send (/home/runner/FCC-express-lessons/node_modules/express/lib/response.js:170:12)
at ServerResponse.json (/home/runner/FCC-express-lessons/node_modules/express/lib/response.js:267:15)
at /home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:108:15
at IncomingMessage. (/home/runner/FCC-express-lessons/node_modules/fcc-express-bground/index.js:33:7)
at IncomingMessage.emit (events.js:315:20)
at IncomingMessage.Readable.read (_stream_readable.js:505:10)
at flow (stream_readable.js:1005:34)
at resume
(_stream_readable.js:986:3) {
code: ‘ERR_HTTP_HEADERS_SENT’
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! fcc-learn-node-with-express@0.1.0 start: node server.js
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the fcc-learn-node-with-express@0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR! /home/runner/.npm/_logs/2021-02-06T10_22_11_569Z-debug.log

I’ve had a look at the FCC’s verification process code here:

And the error appear to occur when parsing the response at line 91 and 99:

try {
        lowerCase = JSON.parse(lowerCase).message;
      } catch (e) {
        console.log(e);
        next(e);
      }
try {
          upperCase = JSON.parse(upperCase).message;
        } catch (e) {
          console.log(e);
          next(e);
        }

Here is the state of my .env file when I initiate the test:

MESSAGE_STYLE=uppercase

Here is a typical api response when MESSAGE_STYLE===undefined:
(taken from the browsers developer tools > Network > Response > Response Payload)

{"message":"Hello json"}

Here is a typical api response when MESSAGE_STYLE===uppercase:
(taken from the browsers developer tools > Network > Response > Response Payload)

{"message":"HELLO JSON"}

Thanks in advance.

Your code so far

var express = require('express');
var app = express();

app.use(express.static(__dirname + "/public"))

app.use(function middleware(req, res, next) {
  const logStr = `${req.method} ${req.path} - ${req.ip}`
  console.log(logStr)
  next()
})

app.get("/", (_,res) => {
  const fileName = __dirname + "/views/index.html"
  res.sendFile(fileName)
})

app.get("/json",(_,res) => {
  let resJson = {message:"Hello json"};
  if (process.env.MESSAGE_STYLE==="uppercase"){
    resJson.message = resJson.message.toUpperCase()
  }
  return res.json(resJson)
})

 module.exports = app;

Your browser information:

User Agent is: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.150 Safari/537.36.

Challenge: Use the .env File

Link to the challenge:

Also the code on repl.it: https://repl.it/@Mormonorman/FCC-express-lessons

I guess this is the issue here: Can't complete challenge: Use the .env File - #2 by nhcarrigan