Do not delete relations if a language record is deleted

composer.json

@@ -25,7 +25,8 @@
     },
     "require-dev": {
         "contao/manager-plugin": "^2.0",
-        "phpunit/phpunit": "^9.5"
+        "phpunit/phpunit": "^9.5",
+        "terminal42/dc_multilingual": "^4.0"
     },
     "conflict": {
         "contao/manager-plugin": "<2.0 || >=3.0"

src/DcaRelationsManager.php

@@ -25,6 +25,7 @@
 use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\HttpFoundation\Session\Attribute\AttributeBagInterface;
 use Symfony\Component\String\UnicodeString;
+use Terminal42\DcMultilingualBundle\Driver;
 
 class DcaRelationsManager
 {
@@ -180,9 +181,13 @@ public function updateRelatedRecords(mixed $value, DataContainer $dc): mixed
     /**
      * Delete the records in related table.
      */
-    public function deleteRelatedRecords(DataContainer $dc, int $undoId): void
+    public function deleteRelatedRecords(DataContainer $dc, int|string $undoId): void
     {
-        $this->deleteRelatedRecordsWithUndo($dc->table, $dc->id, $undoId);
+        if (!$undoId || ($dc instanceof Driver && '' !== $dc->getCurrentLanguage())) {
+            return;
+        }
+
+        $this->deleteRelatedRecordsWithUndo($dc->table, $dc->id, (int) $undoId);
     }
 
     /**
@@ -321,6 +326,10 @@ public function cleanRelatedRecords(): void
             throw new \RuntimeException('There seems to be no valid DataContainer instance!');
         }
 
+        if ($dc instanceof Driver && '' !== $dc->getCurrentLanguage()) {
+            return;
+        }
+
         $this->loadDataContainers();
 
         foreach ($GLOBALS['TL_DCA'] as $table => $dca) {