Various issues in other repos to re-examine

This is more a mental note for myself.

https://github.com/JuliaLang/julia/pull/16080
https://github.com/julialang/julia/issues/16889
https://github.com/JuliaLang/julia/pull/16961
https://github.com/JuliaStats/NullableArrays.jl/pull/115
