Fix Exception when displaying mail_history (PRETIXEU-BB0) (#4934)

* Fix Exception when displaying mail_history

Log entries of type pretix.plugins.banktransfer.order.email.invoice had type(invoices) == int instead of list

* Update src/pretix/control/views/orders.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

---------

Co-authored-by: Raphael Michel <michel@rami.io>
Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/control/views/orders.py

@@ -2491,10 +2491,13 @@ class OrderEmailHistory(EventPermissionRequiredMixin, OrderViewMixin, ListView):
     def get_context_data(self, **kwargs):
         ctx = super().get_context_data(**kwargs)
         for l in ctx["logs"]:
-            if l.parsed_data.get("invoices"):
+            invoice_ids = l.parsed_data.get("invoices")
+            if invoice_ids:
+                if type(invoice_ids) is int:
+                    invoice_ids = [invoice_ids]
                 l.parsed_invoices = Invoice.objects.filter(
                     event=self.request.event,
-                    pk__in=l.parsed_data["invoices"],
+                    pk__in=invoice_ids,
                 )
             if l.parsed_data.get("attach_other_files"):
                 l.parsed_other_files = [

src/pretix/plugins/banktransfer/payment.py

@@ -410,7 +410,7 @@ class BankTransfer(BasePaymentProvider):
                         'message': email_content,
                         'position': None,
                         'recipient': email,
-                        'invoices': invoice.pk,
+                        'invoices': [invoice.pk],
                         'attach_tickets': False,
                         'attach_ical': False,
                     }