a couple of usages of properties that no longer exist couldn't be migrated.
in addition, this revealed a couple of dead properties in the default file.
this is not an ideal solution (I'd much rather model the configs using classes and map them) but in the absence of a good and reliable library to do that, this is the next best thing.
this is not as good as phpstan/phpstan-src#769 (e.g. array_key_first()/array_key_last() aren't covered by this, nor is array_rand()) but it does eliminate the most infuriating cases where this usually crops up.
