Ajax success and error handlers not working with nodejs

For some reason, the success and error handlers of my ajax request is not working as expected.

My node server performs correctly and gives me the right results, but whatever is in the error section of my ajax request executes regardless.

I checked other posts and they seem to be doing the same thing I am. I can't figure out what's happening.

My ajax code:

$.ajax({
        url: path,
        method: 'POST',
        dataType: 'JSON',
        data: items,
        success: function(response)
        {

            alert('Tweety Logs sent successfully.')
        },
        error: function(err)
        {

            alert('Tweety Logs not sent.')
        }
});

The function in my server:

function log(req,res)
{
  var breed = req.body.breed;
  var list = req.body.logs;
  try {
    fs.appendFileSync("Logs/log.dat", JSON.stringify(breed) + "logs:\r\n");
    for(let i = 0; i < list.length; i++)
    {
      fs.appendFileSync("Logs/log.dat", JSON.stringify(list[i])  + "\r\n");
      console.log('Added to Logs/log.dat - ' + JSON.stringify(list[i]));
    }
    res.sendStatus(200);
  }
  catch (err) {
    console.log('Error writing to the file: ' + err.message)
    res.sendStatus(500);
  }
}

The error bit of ajax gets called everytime even if it's successful. Any idea why?