Yes, but this doesn't work in webassembly because 0x0 is a valid address. That's my point. To do .NET & JVM in webassembly requires doing an actual null compari

Yes, but this doesn't work in webassembly because 0x0 is a valid address. That's my point. To do .NET & JVM in webassembly requires doing an actual null comparison and branch as you no longer get to just deref and catch the resulting segfault as there won't be a segfault. So you have to do an actual branch everywhere, which makes null checks way way more expensive.