Mongoose insertMany().exec() returning a TypeError

Question

The following function is called by an async/await function and therefore I need a real Promise to be returned from Mongoose hence the use of ".exec()" per the documentation and this SO thread.

// where data is an array of documents
function insertNewResults(data) {
    return Model.insertMany(data).exec();
}

Doing so gives me the following error:

TypeError: Model.insertMany(...).exec is not a function at insertNewResults

If I remove exec(), I'm able to insertMany without any issues. My other queries using exec() don't seem to be throwing any errors, which makes it all the more perplexing.

Can someone explain why this is happening?

Edit 1: Below is my Schema code

const mongoose = require('mongoose');

const schema = new mongoose.Schema({
    date: { type: Date, required: true },
    price: { type: Number, required: true },
    result: { type: String, required: true }
}, { usePushEach: true });

schema.index(
    { date: -1 }
);
mongoose.model('Model', schema);

Answer 1

As it's explained in the reference, exec() may be needed for methods that return queries because queries are not promises. The reference also lists methods that return queries:

Model.deleteMany()
Model.deleteOne()
Model.find()
Model.findById()
Model.findByIdAndDelete()
Model.findByIdAndRemove()
Model.findByIdAndUpdate()
Model.findOne()
Model.findOneAndDelete()
Model.findOneAndRemove()
Model.findOneAndUpdate()
Model.replaceOne()
Model.updateMany()
Model.updateOne()

insertMany isn't one of them, it returns a promise right away.

It should be:

function insertNewResults(data) {
    return Model.insertMany(data);
}