NGSTACK-672 Properly handle empty fields

Author: Randy Čupić

bundle/Command/RefreshEzFieldsCommand.php

@@ -570,7 +570,7 @@ private function updateNgrmAttribute(array $attribute, Value $value): void
 
         $oldDataText = $attribute['data_text'];
 
-        $oldValue = new Value(json_decode($oldDataText, true));
+        $oldValue = new Value(json_decode($oldDataText, true) ?? []);
         $value->variations = $oldValue->variations;
 
         $newDataText = json_encode($value);