[6.x] Fix return type error

src/Condition/BaseDateRangeConditionRule.php

@@ -16,6 +16,7 @@
 use CraftCms\Cms\Support\Url;
 use DateTimeInterface;
 use Exception;
+use Illuminate\Support\Facades\Date;
 use Illuminate\Validation\Rule;
 use Override;
 
@@ -379,6 +380,12 @@ protected function matchValue(?DateTimeInterface $value): bool
 
     private function _inclusiveEndDate(): DateTimeInterface
     {
-        return DateTimeHelper::toDateTime($this->_endDate)->modify('+1 day');
+        $endDate = DateTimeHelper::toDateTime($this->_endDate);
+
+        if ($endDate === false) {
+            throw new Exception('Invalid end date.');
+        }
+
+        return Date::instance($endDate)->modify('+1 day');
     }
 }

src/Support/DateTimeHelper.php

@@ -72,11 +72,11 @@ class DateTimeHelper
      * @param  bool  $assumeSystemTimeZone  Whether it should be assumed that the value was set in the system timezone if
      *                                      the timezone was not specified. If this is `false`, UTC will be assumed.
      * @param  bool  $setToSystemTimeZone  Whether to set the resulting DateTime object to the system timezone.
-     * @return DateTime|false The DateTime object, or `false` if $object could not be converted to one
+     * @return DateTimeInterface|false The DateTime object, or `false` if $object could not be converted to one
      *
      * @throws Exception
      */
-    public static function toDateTime(mixed $value, bool $assumeSystemTimeZone = false, bool $setToSystemTimeZone = true): DateTime|false
+    public static function toDateTime(mixed $value, bool $assumeSystemTimeZone = false, bool $setToSystemTimeZone = true): DateTimeInterface|false
     {
         if ($value instanceof DateTime) {
             return $value;