Fix: Show voucher without kots and iventories would cause an error in show.

barker/barker/routers/voucher/show.py

@@ -212,8 +212,19 @@ def from_table(
                         )
                     )
                     .unique()
-                    .scalar_one()
+                    .scalar_one_or_none()
                 )
+                if item is None:
+                    item = db.execute(
+                        select(Voucher)
+                        .join(Voucher.food_table)
+                        .join(Voucher.customer, isouter=True)
+                        .where(Voucher.id == v)
+                        .options(
+                            contains_eager(Voucher.food_table),
+                            contains_eager(Voucher.customer),
+                        )
+                    ).scalar_one()
 
                 if guest is not None:
                     item.customer = guest.customer