From 1337f8969fe5f7f133d2c7819f2a99c4dfb4ee17 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 1c253437a..c5dbac97d 100644
--- a/lib/DateTimeParser.php
+++ b/lib/DateTimeParser.php
@@ -104,7 +104,7 @@ public static function parseDuration($duration, $asString = false)
         if (!$asString) {
             $invert = false;
 
-            if ('-' === $matches['plusminus']) {
+            if (isset($matches['plusminus']) && '-' === $matches['plusminus']) {
                 $invert = true;
             }