[BUGFIX] Fix counting of doktypes in DatabaseIntegrityCheck

The previous logic for checking whether a value for a specific
doktype already exists falsely assumed the value should be an
array. This is now fixed by using the null coalescing assignment,
which is available since PHP 7.4.

Resolves: #101196
Related: #94498
Releases: main, 12.4, 11.5
Change-Id: Iab1dba7987d336b08bfb4f398b16666d591daada
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79564


Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>

typo3/sysext/lowlevel/Classes/Integrity/DatabaseIntegrityCheck.php

@@ -154,10 +154,7 @@ class DatabaseIntegrityCheck
                 $this->recStats['hidden']++;
             }
 
-            if (!is_array($this->recStats['doktype'][$row['doktype']] ?? false)) {
-                $this->recStats['doktype'][$row['doktype']] = 0;
-            }
-
+            $this->recStats['doktype'][$row['doktype']] ??= 0;
             $this->recStats['doktype'][$row['doktype']]++;
             // If all records should be shown, do so:
             if ($this->genTreeIncludeRecords) {