TYPO3 Core

For the flag images of my language menu, I got always the following failure from the method \TYPO3\CMS\Core\Utility\GeneralUtility\GifBuilder->fileName().

Serialization of 'Closure' is not allowed.

I think the reason is, there are some anonymous functions in any of the classes \TYPO3\CMS\Core\Resource\File or \TYPO3\CMS\Core\Resource\ProcessedFile which are included in the array setup. You try to serialize this array.
I have found a workaround for myself. I transform the array setup with implode before I serialize it. But I cannot say, if this would lead to trouble in ohter situations. Therefore I know to less about this coding.
Please have a look into the attached dokument. There can you see the workaround from me and the content of the array setup.

Exactly Typo Version is 7.1.0