This will fail (fatal error) with PHP < 5.4. You need to expose the logger in the closure declaration:

~line 84
```php
$logger = $this->logger;
return $this->getLegacyKernel()->runCallback(
    function () use ( $field, $versionInfo, $variationName, &$allAliasHandlers, &$allVariations, $variationIdentifier, $logger )
        // ...
    },
    false
);
```