Investigate null heap handles

[MaulingMonkey]

std goes out of it's way to null-check the result of GetProcessHeap():

https://github.com/rust-lang/rust/blob/ab62d56603293e9264b4d811d2d6f5b49a3264f9/library/std/src/sys/alloc/windows.rs#L94-L99

Investigate if HeapAlloc etc. already null checks, or if ialloc needs adjustment.

[MaulingMonkey]

Wine seems to null check, although it might generate error logs in the process?

https://github.com/rpodgorny/wine/blob/bfb5e181187c32fc63eb8c7e1092fd9f778eee52/dlls/kernel32/heap.c#L269-L272

https://github.com/rpodgorny/wine/blob/bfb5e181187c32fc63eb8c7e1092fd9f778eee52/dlls/ntdll/heap.c#L1655-L1665

https://github.com/rpodgorny/wine/blob/bfb5e181187c32fc63eb8c7e1092fd9f778eee52/dlls/ntdll/heap.c#L441-L448