fix

diff --git a/src/catalogue/templatetags/catalogue_tags.py b/src/catalogue/templatetags/catalogue_tags.py
index b45fc50..57dd1f2 100644 (file)
--- a/src/catalogue/templatetags/catalogue_tags.py
+++ b/src/catalogue/templatetags/catalogue_tags.py
@@ -550,6 +550,8 @@ def content_warning(book):
 @register.inclusion_tag('catalogue/preview_ad.html', takes_context=True)
 def preview_ad(context):
     book = Book.objects.filter(parent=None, preview=True).first()
+    if book is None:
+        return {}
     return {
         'accessible': book.is_accessible_to(context['request'].user),
         'book': book,
@@ -558,6 +560,8 @@ def preview_ad(context):
 @register.inclusion_tag('catalogue/preview_ad_homepage.html', takes_context=True)
 def preview_ad_homepage(context):
     book = Book.objects.filter(parent=None, preview=True).first()
+    if book is None:
+        return {}
     return {
         'accessible': book.is_accessible_to(context['request'].user),
         'book': book,