Unexpected behaviour for `Language::isLast()`

[rasteiner]

Description

The current implementation of $language->isLast() checks if "only one Language is configured in Kirby", and not whether "the language object is the last one in a collection".

Expected behavior
I would expect the isLast function to work like the isFirst function (accept an optional collection and check if it is the first / last object in it). This allows us, for example, to apply specific styles to a language switcher.

Additional context
Current implementation:
https://github.com/getkirby/kirby/blob/5.2.1/src/Cms/Language.php#L341-L347

The function implementation was introduced by the commit 597ccca.

In which "is last" assumes the meaning of "the sole remaining language when deleting them", which in my opinion is a bit unexpected given that the object in kirby is often accessed through a Languages collection which is sortable.

Your setup

Kirby Version
5.2.1

Workaround

I can check if a language is the last object in the collection by using the Collection method ->last() and compare it to the language:

$langsCollection->last()->is($lang)

Proposal

Maybe we can introduce something like a isSole or isLone or hasNoSiblings or something to the HasSiblings trait which does what the current $language->isLast() does.

[afbora]

I think your argument is correct. Looking at Kirby's code in general, the isLast method returns whether the collection has its last element, but here it has a different function.

We can rewrite the isLast method correctly and rewrite the logic inside isDeletable inline.