Various small bug fixes, break out pagination for cards into its own mixin and templatetag

home/views.py

@@ -2,6 +2,7 @@ from collections import defaultdict, OrderedDict
 from django.views.generic import TemplateView
 from django.urls import reverse_lazy
 from django.db.models import Count, Q, Prefetch, Sum, F, IntegerField, Value, BooleanField, Case, When
+from django.db.models.functions import Coalesce
 from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
 from trades.models import TradeOffer, TradeAcceptance, TradeOfferHaveCard, TradeOfferWantCard
 from cards.models import Card
@@ -61,7 +62,9 @@ class HomePageView(TemplateView):
             # Least Offered Cards
             try:
                 context["least_offered_cards"] = (
-                    Card.objects.annotate(offer_count=Sum("tradeofferhavecard__quantity"))
+                    Card.objects.annotate(
+                        offer_count=Coalesce(Sum("tradeofferhavecard__quantity"), 0)
+                    )
                     .order_by("offer_count")[:6]
                 )
             except Exception as e: