3 files changed, 5 insertions, 5 deletions
diff --git a/vendor/sabre/vobject/lib/DateTimeParser.php b/vendor/sabre/vobject/lib/DateTimeParser.php
index 1c253437a..c5dbac97d 100644
--- a/vendor/sabre/vobject/lib/DateTimeParser.php
+++ b/vendor/sabre/vobject/lib/DateTimeParser.php
@@ -104,7 +104,7 @@ class DateTimeParser
         if (!$asString) {
             $invert = false;
 
-            if ('-' === $matches['plusminus']) {
+            if (isset($matches['plusminus']) && '-' === $matches['plusminus']) {
                 $invert = true;
             }
 
diff --git a/vendor/sabre/vobject/lib/ITip/Broker.php b/vendor/sabre/vobject/lib/ITip/Broker.php
index b66a59f54..80d9a5b31 100644
--- a/vendor/sabre/vobject/lib/ITip/Broker.php
+++ b/vendor/sabre/vobject/lib/ITip/Broker.php
@@ -156,9 +156,9 @@ class Broker
      * people. If the user was an attendee, we need to make sure that the
      * organizer gets the 'declined' message.
      *
-     * @param VCalendar|string $calendar
-     * @param string|array     $userHref
-     * @param VCalendar|string $oldCalendar
+     * @param VCalendar|string      $calendar
+     * @param string|array          $userHref
+     * @param VCalendar|string|null $oldCalendar
      *
      * @return array
      */
diff --git a/vendor/sabre/vobject/lib/Version.php b/vendor/sabre/vobject/lib/Version.php
index 63349e47e..c7ca69e14 100644
--- a/vendor/sabre/vobject/lib/Version.php
+++ b/vendor/sabre/vobject/lib/Version.php
@@ -14,5 +14,5 @@ class Version
     /**
      * Full version number.
      */
-    public const VERSION = '4.5.3';
+    public const VERSION = '4.5.4';
 }