Hi guys - working on a personal project need some help in my REST API :)

   const itemSchema = new Schema({
            type:String,
            brand:String,
        description:String,
            model:String,
            price:Number,
        createdAt:{type: Date, default: Date.now},
        updatedAt:{type: Date, default: Date.now}
    });

    itemSchema.statics.findBrand = function(brand, callback){ 
        return this.find({brand: brand}, callback);
    }

    itemSchema.statics.findType = function(type, callback){
        return this.find({type: type}, callback);
    }

    itemSchema.methods.findSameBrand = function(callback){
        // this == docuemnt
        return this.model("Item").find({type: this.type}, callback);
    }


    itemSchema.method("update", function(updates, callback){
        Object.assign(this, updates, { updatedAt: new Date() });
        this.parent().save(callback);
    });

    const Item = mongoose.model("Item", itemSchema);

    const mouse = new Item({
        type: "Mouse",
        brand: "Logitech",
        description: "Simple, yet elegant.",
        model: "G102",
        price: 3000
    });

    const itemData = [
        {
            type: "Mouse",
            brand: "Corsair",
            description: "2",
            model: "G104",
            price: 8000   
        },
        {
            type: "Mouse",
            brand: "Razer",
            description: "3",
            model: "G103",
            price: 2000   
        }, 
        {
            type: "Keyboard",
            brand: "Razer",
            description: "3",
            model: "G103",
            price: 2000   
        }, 
        mouse 
    ] 

    Item.remove({}, function(err) {
        if (err) console.error(err);

        Item.create(itemData, function(err, items) {
            if(err) console.error(err);

            Item.findOne({type: "Mouse"}, function(err, mouse){

                mouse.findSameBrand( (err, items) => {
                    if (err) console.error(err);

                    items.forEach( items => {
                        console.log(`Type: ${items.type} - Brand: ${items.brand} Price: ${items.brand} `);
                    });
                });

                db.close( () => {
                    console.log("connection closed");
                });

            });

        });

    });

events.js:182
      throw er; // Unhandled 'error' event
      ^

TypeError: this.model is not a function