The crash happens on 1.20.1, with Litematica 0.15.3, malilib 0.16.3.
When starting any solo world or server, the game freezes after a short amount of time - about 2 seconds - and then crashes.

According to TooManyCrashes, Iris and Sodium may be involved, but even when disabling those mods, they still show up as potential causes of the crash, which seems strange. Valkyrien Skies 2 is also said to be involved, and removing the mod actually prevents the game from crashing, so I'm assuming the crash comes from there.

The crash log is attached below.

crash-2024-07-24_18.18.00-client.txt

This is caused by Valkyrien Skies. In this case it seems to happen via Sodium, apparently Valkyrien Skies is mixing into Sodium code. Someone else reported that removing either Sodium or Valkyrien Skies would prevent the crash, but I haven't tested it myself.

There isn't really anything "easy" I can do from my side for now, as Valkyrien Skies tries to cast my schematic world into a vanilla client world, although it doesn't extend it, so that will crash.