I'm trying to update the document but the error says the query has already been executed.

• MongooseError: Query was already executed: footballs.updateOne({ date: 'January 4' }, {})*

app.post('/api/bookslot', async (req, res) => {
  console.log(req.body);
  try {
    const token = req.headers['x-access-token'];
    const decoded = jwt.verify(token, 'secret123');
    const email = decoded.email;
    const user = await UserModel.findOne({ email: email });

    let sportname = req.body.selectedSport.toLowerCase();
    const time = req.body.slotTime;
    const seats = req.body.availableSeats - 1;

    if (!sportname.endsWith('s')) {
      sportname = sportname.concat('s');
    }
    const NewSlotModel = mongoose.model(sportname, slotSchema);
    var update = {};
    update[time] = seats - 1;
    console.log(update);
    const a = await NewSlotModel.updateOne(
      { date: req.body.slotDate },
      { $set: update },
      function (err, success) {
        if (err) return handleError(err);
      }
    );

    return res.json({ status: 'ok' });
  } catch (e) {
    console.log(e);
    res.json({ status: 'error' });
  }
});

where am I going wrong?