From 877165f4ed6d2063b384e73de32ecd154b7cb805 Mon Sep 17 00:00:00 2001
From: Ludovic Marcotte <lmarcotte@inverse.ca>
Date: Tue, 17 May 2016 11:18:40 -0400
Subject: [PATCH] (fix) safe guard against bogus tz offset definition

---
 SOPE/NGCards/iCalTimeZonePeriod.m | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/SOPE/NGCards/iCalTimeZonePeriod.m b/SOPE/NGCards/iCalTimeZonePeriod.m
index 23d56ba8e..b31e30e82 100644
--- a/SOPE/NGCards/iCalTimeZonePeriod.m
+++ b/SOPE/NGCards/iCalTimeZonePeriod.m
@@ -63,6 +63,10 @@
   offsetTo = [[self uniqueChildWithTag: offsetName]
                flattenedValuesForKey: @""];
   length = [offsetTo length];
+
+  if (!length)
+    return seconds;
+
   negative = [offsetTo hasPrefix: @"-"];
   if (negative)
     {