Also didn't notice a particular case here, but if all code passes up
until we get to the `foreach (var h in nestedHitObjects)` below, then we
could end up stuck here for quite a while.
See previous commit for partial rationale.
There's an argument to be made about the `NaN`-spreading semantics being
desirable because at least something will loudly fail in that case, but
I'm not so sure about that these days. It feels like either way if
`NaN`s are produced, then things are outside of any control, and chances
are the game can probably continue without crashing. And, this move
reduces our dependence on osuTK, which has already been living on
borrowed time for years now and is only awaiting someone brave to go
excise it.