How to make Mongoose ignore empty values ​​in an array, with a unique parameter?

Question

JavaScript

I have a schema

const schema = new mongoose.Schema({
    ...account,
    characters : [
        { ...character },
    ],
    stats,
});

const character = {
    name: { type: String, required: true, unique: true },
}

When creating a user with an empty character array, I get a mongoose error

admin.players index: characters.name_1 dup key: { : null }

How to make it so that unique is checked only for those arrays that are created?

Answer 1

setting sparse: true solves the problem, but values ​​can be repeated in this array, except for arrays of other documents...