Fixed issues #4134 undefined array index label_use_default in Mage_Ca…

…talog_Model_Product_Attribute_Backend_Media (#4136)

* fix issues 4134

* better code
Co-authored-by: kiatng

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Co-authored-by: Ng Kiat Siong <kiatsiong.ng@gmail.com>

app/code/core/Mage/Catalog/Model/Product/Attribute/Backend/Media.php

@@ -167,11 +167,13 @@ public function beforeSave($object)
         foreach ($value['values'] as $mediaAttrCode => $attrData) {
             if (array_key_exists($attrData, $newImages)) {
                 $object->setData($mediaAttrCode, $newImages[$attrData]['new_file']);
-                $object->setData($mediaAttrCode . '_label', ($newImages[$attrData]['label'] === null || $newImages[$attrData]['label_use_default']) ? $newImages[$attrData]['label_default'] : $newImages[$attrData]['label']);
+                $label = $newImages[$attrData]['label'] === null || !empty($newImages[$attrData]['label_use_default']) ? $newImages[$attrData]['label_default'] : $newImages[$attrData]['label'];
+                $object->setData($mediaAttrCode . '_label', $label);
             }
 
             if (array_key_exists($attrData, $existImages)) {
-                $object->setData($mediaAttrCode . '_label', ($existImages[$attrData]['label'] === null || $existImages[$attrData]['label_use_default']) ? $existImages[$attrData]['label_default'] : $existImages[$attrData]['label']);
+                $label = $existImages[$attrData]['label'] === null || !empty($existImages[$attrData]['label_use_default']) ? $existImages[$attrData]['label_default'] : $existImages[$attrData]['label'];
+                $object->setData($mediaAttrCode . '_label', $label);
             }
         }