diff --git a/lam/lib/baseModule.inc b/lam/lib/baseModule.inc
index aaa936156..b5a521268 100644
--- a/lam/lib/baseModule.inc
+++ b/lam/lib/baseModule.inc
@@ -1268,10 +1268,10 @@ abstract class baseModule {
 	* <br>
 	* It allows additional LDAP changes when an account is deleted.
 	*
-	* @return List of LDAP operations, same as for save_attributes()
+	* @return array of LDAP operations, same as for save_attributes()
 	*/
-	public function delete_attributes() {
-		return 0;
+	public function delete_attributes(): array {
+		return [];
 	}
 
 	/**
diff --git a/lam/lib/modules/nisNetGroupUser.inc b/lam/lib/modules/nisNetGroupUser.inc
index 29acd9e33..273a89906 100644
--- a/lam/lib/modules/nisNetGroupUser.inc
+++ b/lam/lib/modules/nisNetGroupUser.inc
@@ -386,18 +386,17 @@ class nisNetGroupUser extends baseModule {
 	}
 
 	/**
-	* Additional LDAP operations on delete.
-	*
-	* @return List of LDAP operations, same as for save_attributes()
-	*/
-	function delete_attributes() {
+	 * {@inheritDoc}
+	 * @see baseModule::delete_attributes()
+	 */
+	function delete_attributes(): array {
 		$uid = $this->getUid();
 		if (empty($uid)) {
-			return array();
+			return [];
 		}
-		$return = array();
+		$return = [];
 		// remove from NIS netgroups
-		$changes = array();
+		$changes = [];
 		foreach ($this->groups as $group) {
 			$changes[$group['dn']][] = $this->createNetGroupValue($group, $uid);
 		}
diff --git a/lam/lib/modules/posixAccount.inc b/lam/lib/modules/posixAccount.inc
index b15455b6b..3025c85b9 100644
--- a/lam/lib/modules/posixAccount.inc
+++ b/lam/lib/modules/posixAccount.inc
@@ -998,12 +998,11 @@ class posixAccount extends baseModule implements passwordService,AccountStatusPr
 	}
 
 	/**
-	* Additional LDAP operations on delete.
-	*
-	* @return List of LDAP operations, same as for save_attributes()
-	*/
-	function delete_attributes() {
-		$return = array();
+	 * {@inheritDoc}
+	 * @see baseModule::delete_attributes()
+	 */
+	function delete_attributes(): array {
+		$return = [];
 		// remove memberUids if set
 		$groups = searchLDAPByAttribute('memberUid', $this->attributes['uid'][0], 'posixGroup', array('dn'), array('group'));
 		for ($i = 0; $i < sizeof($groups); $i++) {
diff --git a/lam/lib/modules/posixGroup.inc b/lam/lib/modules/posixGroup.inc
index 0108f1a66..cc3b065b4 100644
--- a/lam/lib/modules/posixGroup.inc
+++ b/lam/lib/modules/posixGroup.inc
@@ -164,12 +164,11 @@ class posixGroup extends baseModule implements passwordService {
 	}
 
 	/**
-	* Checks if the group which should be deleted is still used as primary group.
-	*
-	* @return List of LDAP operations, same as for save_attributes()
-	*/
-	function delete_attributes() {
-		$return = array();
+	 * {@inheritDoc}
+	 * @see baseModule::delete_attributes()
+	 */
+	function delete_attributes(): array {
+		$return = [];
 		$result = searchLDAPByFilter('(&(objectClass=posixAccount)(gidNumber=' . $this->attributes['gidNumber'][0] . '))', array('dn'), array('user', 'host'));
 		if (sizeof($result) > 0) {
 			$max = 5;
diff --git a/lam/templates/delete.php b/lam/templates/delete.php
index 9376df34a..50dd8f5e6 100644
--- a/lam/templates/delete.php
+++ b/lam/templates/delete.php
@@ -229,20 +229,18 @@ if (isset($_POST['delete'])) {
 			foreach ($moduleNames as $singlemodule) {
 				// load changes
 				$temp = $modules[$singlemodule]->delete_attributes();
-				if (is_array($temp)) {
-					// merge changes
-					$DNs = array_keys($temp);
-					$attributes = array_merge_recursive($temp, $attributes);
-					foreach ($DNs as $dn) {
-						$ops = array_keys($temp[$dn]);
-						foreach ($ops as $op) {
-							$attrs = array_keys($temp[$dn][$op]);
-							foreach ($attrs as $attribute) {
-								$attributes[$dn][$op][$attribute] = array_unique($attributes[$dn][$op][$attribute]);
-							}
-						}
-					}
-				}
+                // merge changes
+                $DNs = array_keys($temp);
+                $attributes = array_merge_recursive($temp, $attributes);
+                foreach ($DNs as $dn) {
+                    $ops = array_keys($temp[$dn]);
+                    foreach ($ops as $op) {
+                        $attrs = array_keys($temp[$dn][$op]);
+                        foreach ($attrs as $attribute) {
+                            $attributes[$dn][$op][$attribute] = array_unique($attributes[$dn][$op][$attribute]);
+                        }
+                    }
+                }
 			}
 			$DNs = array_keys($attributes);
 			foreach ($DNs as $dn) {
diff --git a/lam/templates/tools/multiEdit.php b/lam/templates/tools/multiEdit.php
index 8b63e2e1c..01b96d511 100644
--- a/lam/templates/tools/multiEdit.php
+++ b/lam/templates/tools/multiEdit.php
@@ -479,18 +479,16 @@ function dryRun(): array {
 	$tempFilesManager = new LamTemporaryFilesManager();
 	$fileName = $tempFilesManager->registerTemporaryFile('.ldif', 'ldif_');
 	$out = $tempFilesManager->openTemporaryFileForWrite($fileName);
-	if ($out !== false) {
-		fwrite($out, $ldif);
-		$container->addElement(new htmlOutputText(_('LDIF file')), true);
-		$ldifLink = new htmlLink($fileName, $tempFilesManager->getDownloadLink($fileName));
-		$ldifLink->setTargetWindow('_blank');
-		$container->addElement($ldifLink, true);
-		$container->addVerticalSpace('20px');
-		$container->addElement(new htmlOutputText(_('Log output')), true);
-		$container->addElement(new htmlInputTextarea('log', $log, 100, 30), true);
-		// generate HTML
-		fclose ($out);
-	}
+	fwrite($out, $ldif);
+	$container->addElement(new htmlOutputText(_('LDIF file')), true);
+	$ldifLink = new htmlLink($fileName, $tempFilesManager->getDownloadLink($fileName));
+	$ldifLink->setTargetWindow('_blank');
+	$container->addElement($ldifLink, true);
+	$container->addVerticalSpace('20px');
+	$container->addElement(new htmlOutputText(_('Log output')), true);
+	$container->addElement(new htmlInputTextarea('log', $log, 100, 30), true);
+	// generate HTML
+	fclose ($out);
 	ob_start();
 	parseHtml(null, $container, array(), true, 'user');
 	$content = ob_get_contents();
diff --git a/rector.php b/rector.php
index 3265a2a4e..281700713 100644
--- a/rector.php
+++ b/rector.php
@@ -1,6 +1,7 @@
 <?php
 
 use Rector\Config\RectorConfig;
+use Rector\Set\ValueObject\LevelSetList;
 use Rector\Set\ValueObject\SetList;
 
 return static function (RectorConfig $rectorConfig): void {