Fix LabelFormField for objects without labels

LabelHandler will return an empty array if no label was attached to an object, which will result in undefined offset error in the LabelFormField

diff --git a/wcfsetup/install/files/lib/system/form/builder/field/label/LabelFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/label/LabelFormField.class.php
index ce3d6476a7dde0c6d598c999703c4db08abdbba6..8d8351193974b98b65382ae0d6e678f259a3ae03 100644 (file)
--- a/wcfsetup/install/files/lib/system/form/builder/field/label/LabelFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/label/LabelFormField.class.php
@@ -105,10 +105,11 @@ class LabelFormField extends AbstractFormField implements IObjectTypeFormNode {
                                static::$loadedLabels[$objectTypeID] = [];
                        }
                        if (!isset(static::$loadedLabels[$objectTypeID][$objectID])) {
-                               static::$loadedLabels[$objectTypeID][$objectID] = LabelHandler::getInstance()->getAssignedLabels(
+                               $assignedLabels = LabelHandler::getInstance()->getAssignedLabels(
                                        $objectTypeID,
                                        [$objectID]
-                               )[$objectID];
+                               );
+                               static::$loadedLabels[$objectTypeID][$objectID] = isset($assignedLabels[$objectID]) ? $assignedLabels[$objectID] : [];
                        }
                        
                        $labelIDs = $this->getLabelGroup()->getLabelIDs();