IllegalAccessError when trying to check for blocks in world

[Partonetrain]

I'm trying to check for certain blocks in the world through some clever scripting, like so:

import mods.zensummoning.SummoningDirector;
import mods.zensummoning.SummoningAttempt;
import mods.zensummoning.SummoningInfo;
import mods.zensummoning.MobInfo;

import crafttweaker.api.block.Block;
import crafttweaker.api.util.math.BlockPos;
import crafttweaker.api.world.Level;

SummoningDirector.addSummonInfo(
    SummoningInfo.create()
        .setCatalyst(<item:minecraft:stick>)
        .setConsumeCatalyst(false)
        .setReagents([<item:minecraft:diamond>])
        .addMob(MobInfo.create()
            .setMob(<entityType:minecraft:cow>)
            .setCount(4)
            .setOffset(0,4,0)
            .setSpread(1,1,1)
        )
        .setMutator((attempt as SummoningAttempt) => {
            if (CheckBlocks(attempt, 0, -1, 0) == <block:minecraft:iron_block>)  {
                attempt.success = false;
                attempt.message = "Need an iron block!";
            } else {
                attempt.message = "Woohoo!";
            }
        })
);

function CheckBlocks(attempt as SummoningAttempt, x as int, y as int, z as int) as Block{
    return ((attempt.world.getBlockState(attempt.pos.offset(x, y, z)).block));
}

But this crashes the game:

Error: java.lang.IllegalAccessError: class j_util_function_Consumer_1 tried to access method 'net.minecraft.world.level.block.Block scripts.summons.CheckBlocks(ca.teamdman.zensummoning.common.summoning.SummoningAttempt, int, int, int)' (j_util_function_Consumer_1 and scripts.summons are in unnamed module of loader org.openzen.zenscript.javabytecode.JavaBytecodeRunUnit$ScriptClassLoader @132ba2ab)

I recognize this is probably not an intended feature of the mod, but it would be really nice to have. Let me know if there's a better way to do this, or if I shouldn't be trying at all :P

[TeamDman]

This is definitely an intended feature, seems the problem is that the mutator lambda can't see the method.

I was able to get it to work with this

import mods.zensummoning.SummoningDirector;
import mods.zensummoning.SummoningAttempt;
import mods.zensummoning.SummoningInfo;
import mods.zensummoning.MobInfo;

import crafttweaker.api.block.Block;
import crafttweaker.api.util.math.BlockPos;
import crafttweaker.api.world.Level;

SummoningDirector.addSummonInfo(
    SummoningInfo.create()
        .setCatalyst(<item:minecraft:stick>)
        .setConsumeCatalyst(false)
        .setReagents([<item:minecraft:diamond>])
        .addMob(MobInfo.create()
            .setMob(<entityType:minecraft:cow>)
            .setCount(4)
            .setOffset(0,4,0)
            .setSpread(1,1,1)
        )
        .setMutator((attempt as SummoningAttempt) => {
            if (attempt.world.getBlockState(attempt.pos.offset(0,-1,0)).block != <block:minecraft:iron_block>) {
                attempt.success = false;
                attempt.message = "Need an iron block!";
            } else {
                attempt.message = "Woohoo!";
            }
        })
);

(I also fixed the equality check in the if statement)

LMK if still has issues :D