From f1c693669ccbbb301121ce3768ef6e647fce5b95 Mon Sep 17 00:00:00 2001
From: Alex <a.ovcharov@gmail.com>
Date: Tue, 20 Jun 2023 10:19:11 +0300
Subject: [PATCH] fixed issue: Undefined index: plusminus #467

https://github.com/sabre-io/vobject/issues/467
---
 lib/DateTimeParser.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/DateTimeParser.php b/lib/DateTimeParser.php
index 4a71931a2..5ce9f207a 100644
--- a/lib/DateTimeParser.php
+++ b/lib/DateTimeParser.php
@@ -93,7 +93,7 @@ public static function parseDuration(string $duration): \DateInterval
 
         $invert = false;
 
-        if ('-' === $matches['plusminus']) {
+        if (isset($matches['plusminus']) && '-' === $matches['plusminus']) {
             $invert = true;
         }