From 6c2f86b7b71105688af82362e2ffbaf49ea76262 Mon Sep 17 00:00:00 2001
From: Charles Haley <github@charles.haleys.org>
Date: Mon, 23 Nov 2015 18:49:20 +0100
Subject: [PATCH] Fix crash when books in GST don't have ratings

---
 src/calibre/db/categories.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/db/categories.py b/src/calibre/db/categories.py
index f209138f54..6db8befa1d 100644
--- a/src/calibre/db/categories.py
+++ b/src/calibre/db/categories.py
@@ -213,7 +213,7 @@ def get_categories(dbcache, sort='name', book_ids=None, first_letter_sort=False)
                             total_rating = 0
                             count = 0
                             for id_ in t.id_set:
-                                rating = book_rating_map[id_]
+                                rating = book_rating_map.get(id_, 0)
                                 if rating:
                                     total_rating += rating/2
                                     count += 1