Can't seem to find what is crashing Minecraft when loading into a new world

[Aparisiu]

The game crashed whilst unexpected error Error: java.lang.ClassCastException: class net.minecraft.client.multiplayer.ClientLevel cannot be cast to class net.minecraft.server.level.ServerLevel (net.minecraft.client.multiplayer.ClientLevel and net.minecraft.server.level.ServerLevel are in module [email protected] of loader 'TRANSFORMER' @365cef67)

Error: -1

 

How can I find what mod is doing this?

[Atralik]

Is it a server or private minecraft world?

You also should be able to find it in a crash reports