Fix some reported issues

Author: dtdesign

wcfsetup/install/files/lib/acp/form/LabelGroupAddForm.class.php

@@ -222,6 +222,7 @@ public function saved()
             );
 
             if ($this->formAction === 'create') {
+                \assert(isset($group));
                 (new LabelGroupEditor($group))->update(['groupName' => $languageItem]);
             } else {
                 (new LabelGroupEditor($this->formObject))->update(['groupName' => $languageItem]);

wcfsetup/install/files/lib/data/label/group/ViewableLabelGroup.class.php

@@ -275,7 +275,7 @@ public function sortLabelsAlphabetically(): void
             $this->labels,
             static fn(Label $a, Label $b) => $collator->compare($a->getTitle(), $b->getTitle())
         );
-        $this->indexToObject = \array_values(\array_keys($this->labels));
+        $this->indexToObject = \array_keys($this->labels);
     }
 
     /**

wcfsetup/install/files/lib/system/cache/builder/LabelCacheBuilder.class.php

@@ -48,6 +48,7 @@ protected function rebuild(array $parameters)
 
         // assign permissions for each label group
         foreach ($data['groups'] as $groupID => $group) {
+            // @phpstan-ignore function.impossibleType, instanceof.alwaysFalse
             \assert($group instanceof ViewableLabelGroup);
 
             // group permissions