Force evaluation of template responses in frontend

src/pretix/presale/middleware.py

@@ -1,3 +1,4 @@
+from django.template.response import TemplateResponse
 from django.urls import resolve
 from django_scopes import scope
 
@@ -29,4 +30,7 @@ class EventMiddleware:
                 for receiver, r in process_response.send(request.event, request=request, response=response):
                     response = r
 
+            if isinstance(response, TemplateResponse):
+                response = response.render()
+
         return response