Property 'includes' is missing in type 'Observable<IProduct[]>'

If this question comes from the Angular course on Pluralsight by @DeborahKurata, the answer is in the next module, "Subscribing to an Observable".

In the ngOnInit(): void method in product-list.component.ts, change this

    this.products = this._productService.getProducts();
    this.filteredProducts = this.products;

to

    this._productService.getProducts()
        .subscribe(products => { 
            this.products = products; 
            this.filteredProducts = this.products; 
        }, error => this.errorMessage = <any>error);