Crash Entering World: class_1297.method_5765() because "$$1" is null

What the log looks like

java\.lang\.NullPointerException: Cannot invoke "net\.minecraft\.class_1297\.method_5765\(\)" because "\$\$1" is null
java\.lang\.NullPointerException: Cannot invoke "net\.minecraft\.entity\.Entity\.hasVehicle\(\)" because "\$\$1" is null

How to fix it

1. Verify the exact Minecraft version of every jar in your mods folder—on 1.21.x, mods made for 1.21.6, 1.21.8, 1.21.9, and 1.21.10 are often not interchangeable.
2. Update Sodium and Iris to the latest builds explicitly tagged for your exact Minecraft version (for example, do not use a +mc1.21.9 build of Sodium on Minecraft 1.21.10).
3. Open your logs/latest.log file and scroll just above the crash report to look for an earlier integrated server exception, which will name any content mod (such as Filament or a biome mod) that failed to initialize the world.
4. If latest.log does not name a culprit, sort your mods folder by filename and remove any mod whose version tag does not match your exact Minecraft sub-version, then test creating a new world.

Check your own log