How to handle the date handler option in plugins using date/modified


i am trying to solve an issue with my autoid plugin. when the kirby date handler option is set to strftime the $page->modified() does not return an integer (timestamp) anymore.
i implemented typehinting so luckily this issue was caught before doing any damage.

i guess the current behaviour is fine considering consistency (and code) but will this require all plugins working with dates to force their format? i guess so.

an example can be found here:

$commitsPage = static::commitEntry(
  $commitsPage, $autoid, $page->id(), 
  null, null, 
  $page->modified() // <-- might be int or string

would this be the proper way to do that instead?

$page->modified('U', 'date')

this might be interesting for a lot of plugins like feed and sitemap from @omz13 and retour from @distantnative.