How to get related ManyToMany objects from different model and render them in HTML format?

Question

I tried to look up the order class and get the last 5 orders with their customer and items. But got the following exception:

*Exception Type:    ValueError
Exception Value:    
Negative indexing is not supported.*

Here are the models:

class Customer(models.Model):
    first_name = models.CharField(max_length=255)
    last_name = models.CharField(max_length=255)
   

class Order(models.Model):
    placed_at = models.DateTimeField(auto_now_add=True)
    customer = models.ForeignKey(Customer, on_delete=models.PROTECT)


class OrderItem(models.Model):
    order = models.ForeignKey(Order, on_delete=models.PROTECT)
    product = models.ForeignKey(Product, on_delete=models.PROTECT)

And here is the view class:

def last_5_orders(request):
    orders = Order.objects.select_related('customer').prefetch_related('orderitem_set__product').order_by('placed_at')[-5:]
    return render(request, 'last_5_orders.html', {'orders': orders})

And finally in last_5_orders.html file I have:

{% for order in orders %}
    <h1>
        {{ order.id }} : {{ order.custumer.first_name }} {{ order.custumer.last_name }} PURCHASED {{order.orderitem_set.product}}
    </h1>
{% endfor %}

Any ideas about resolving this issue?