From 4434665d94d31ac2ffcd91321f97f690883897bb Mon Sep 17 00:00:00 2001
From: Damien Elmes <git@ichi2.net>
Date: Fri, 3 Oct 2008 18:13:01 +0900
Subject: [PATCH] add safety check to interval calcuation

---
 anki/deck.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/anki/deck.py b/anki/deck.py
index a75a8a1ac..e2c0d3788 100644
--- a/anki/deck.py
+++ b/anki/deck.py
@@ -357,6 +357,7 @@ where isDue = 1""")
             elif ease == 4:
                 factor = card.factor * self.factorFour
                 interval = (card.interval + delay) * factor
+            assert card.fuzz
             interval *= card.fuzz
         if self.maxScheduleTime:
             interval = min(interval, self.maxScheduleTime)