refactor: move user existence check into create_grant_card

Each card function now handles its own requirements internally,
keeping the view layer clean and making it easier to add new cards.

Co-authored-by: Marco Acierno <marcoacierno@users.noreply.github.com>

Author: github-actions[bot]

backend/integrations/plain_cards.py

@@ -3,7 +3,11 @@
 
 
 def create_grant_card(request, user, conference):
-    grant = Grant.objects.of_user(user).for_conference(conference).first()
+    grant = (
+        Grant.objects.of_user(user).for_conference(conference).first()
+        if user
+        else None
+    )
 
     if not grant:
         return {"key": "grant", "components": []}

backend/integrations/views.py

@@ -32,9 +32,6 @@ def plain_customer_cards(request):
 
     cards = []
     if "grant" in card_keys:
-        if user:
-            cards.append(create_grant_card(request, user, conference))
-        else:
-            cards.append({"key": "grant", "components": []})
+        cards.append(create_grant_card(request, user, conference))
 
     return Response({"cards": cards})