I'm receiving this error with the Coalan Async library.

Error: (node:2172) UnhandledPromiseRejectionWarning: Error: Callback was already called.

Here is my code:

const updateOrCreateTrips = (trips, done) => {
  const Trip = mongoose.connection.db.collection(...);
    console.log(`updating or creating ${trips.length} trips`);
    async.eachLimit(trips, 100, (trip, next) => {
    const {...rest} = trip;
    console.log(`updating trip (${id}) ${title}`);

     const tripToUpdate = {//some data here...}
     Trip.update(
        {
          _id: trip.wordpressId,
        },
        {
          $set: tripToUpdate,
          $setOnInsert: {
            created: new Date(),
            enabled: true,
          },
        },
        {
          upsert: true,
        },
        next
    );
  }, done);
};