Stringfilter with ArrayValue leads to Warning: addcslashes() expects parameter 1 to be string, array given

@zuernBernhard
Thanks for providing a workaround for making adaptable block php8.1 compatible. I've added an additional check on the type of the $item['value'] as without this it may break in cases, where $item['value'] already is a string.

In general, I agree that we need to cleanup values in the element's storage to fix these issues at the root. I will try to provide an update hook soon.

Thank you - I think we will deploy this today.