handle orders with no products

shop/models.py

@@ -90,6 +90,7 @@ class Order(CreatedUpdatedModel):
 
     @property
     def total(self):
+        if self.products.all():
             return Decimal(self.products.aggregate(
                 sum=Sum(
                     models.F('orderproductrelation__product__price') *
@@ -97,6 +98,8 @@ class Order(CreatedUpdatedModel):
                     output_field=models.IntegerField()
                 )
             )['sum'])
+        else:
+            return False
 
     def get_coinify_callback_url(self, request):
         return 'https://' + request.get_host() + str(reverse_lazy('shop:coinify_callback', kwargs={'pk': self.pk}))