[BUGFIX] Fix SchedulerDatabaseStorageMigration upgrade wizard

Field tx_scheduler_task:tasktype is nullable and therefore
created with NULL as default value.

The SchedulerDatabaseStorageMigration upgrade wizard
only compared it to an empty string, ignoring cases where
the field is null.

Resolves: #107512
Releases: main
Change-Id: I367830c778b495971e42165b0588c489531c2879
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/90749
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Garvin Hicking <garvin@hick.ing>
Reviewed-by: Garvin Hicking <garvin@hick.ing>

Author: linawolf

typo3/sysext/scheduler/Classes/Migration/SchedulerDatabaseStorageMigration.php

@@ -172,7 +172,13 @@ protected function getPreparedQueryBuilder(): QueryBuilder
             ->from(self::TABLE_NAME)
             ->where(
                 $queryBuilder->expr()->eq('deleted', $queryBuilder->createNamedParameter(0, ParameterType::INTEGER)),
-                $queryBuilder->expr()->eq('tasktype', $queryBuilder->createNamedParameter(''))
+                $queryBuilder->expr()->or(
+                    $queryBuilder->expr()->eq(
+                        'tasktype',
+                        $queryBuilder->createNamedParameter('')
+                    ),
+                    $queryBuilder->expr()->isNull('tasktype')
+                )
             );
 
         return $queryBuilder;