for some reason the presence of the type problems were reported as
problems on ChunkUtils.php, despite being outside of the project scope
and the errors not applying to the polyfill.
iterable types are a big pain in the ass because of pthreads' awful architecture, and there's nothing I can do about that without BC-breaking changes to pthreads.
these are non-dependent on environment, so they can be determined with no external input.
This fixes 2 PHPStan issues, fixes some code that couldn't run outside of PM, and makes it easier to write code that depends on PM.
this is much easier to use than devtools, and allows us to make additional specializations for PM build that would otherwise just be a colossal pain in the ass.
