Fix invoice delete

nummi/main/models.py

@@ -300,7 +300,7 @@ class Invoice(CustomModel):
         return str(self.name)
 
     def delete(self, *args, **kwargs):
-        self.file.delete(missing_ok=True)
+        self.file.delete()
         super().delete(*args, **kwargs)
 
     def get_absolute_url(self):

nummi/main/views.py

@@ -247,8 +247,14 @@ class InvoiceDeleteView(NummiDeleteView):
         return reverse_lazy("transaction", kwargs={"pk": self.object.transaction.pk})
 
     def get_queryset(self):
-        return super.get_queryset().filter(
-            transaction=get_object_or_404(Transaction, pk=self.kwargs["transaction_pk"])
+        return (
+            super()
+            .get_queryset()
+            .filter(
+                transaction=get_object_or_404(
+                    Transaction, pk=self.kwargs["transaction_pk"]
+                )
+            )
         )