With the fix to #518 (1e1aa7f), Mixin tries to pretty print a field (asm field) with SignaturePrinter (works only with methods)

This doesn't crash in Mixin 0.8.4.

Type.getReturnType(desc) and Type.getArgumentTypes(desc): Expects a description with ):

TypeUtils uses it:

TypeHandleASM uses it for anonymous classes for fields:

Mixin: (0.8.5 on 1.18 ForgeGradle)

@Mixin(targets = "net.minecraft.server.level.ServerPlayer$2")
public class ServerPlayerEntityMixin {
    @Shadow
    ServerPlayer f_143458_;
}