NMS Help PathFinders

So im getting errors on just one pathfinder and cant seem why and also the pathfinders work just when i spawn the zombie, it can barely move

Code:

package Main;

import java.lang.reflect.Field;

import org.bukkit.craftbukkit.v1_7_R4.util.UnsafeList;

import net.minecraft.server.v1_7_R4.EntityPig;
import net.minecraft.server.v1_7_R4.EntitySkeleton;
import net.minecraft.server.v1_7_R4.EntityZombie;
import net.minecraft.server.v1_7_R4.PathfinderGoalMeleeAttack;
import net.minecraft.server.v1_7_R4.PathfinderGoalNearestAttackableTarget;
import net.minecraft.server.v1_7_R4.World;
public class CustomEntityZombie extends EntityZombie {
     public CustomEntityZombie(World world) {
            super(world);
            try {
                Field bField = PathfinderGoalSelector.class.getDeclaredField("b");
                bField.setAccessible(true);
                Field cField = PathfinderGoalSelector.class.getDeclaredField("c");
                cField.setAccessible(true);
                bField.set(goalSelector, new UnsafeList<PathfinderGoalSelector>());
                bField.set(targetSelector, new UnsafeList<PathfinderGoalSelector>());
                cField.set(goalSelector, new UnsafeList<PathfinderGoalSelector>());
                cField.set(targetSelector, new UnsafeList<PathfinderGoalSelector>());
            } catch (Exception exc) {
                exc.printStackTrace();
            }
            this.goalSelector.a(0, new PathfinderGoalFloat(this));
            this.goalSelector.a(2, new PathfinderGoalMeleeAttack(this,EntityPig.class, 1.0D, false));
            this.goalSelector.a(2, new PathfinderGoalMeleeAttack(this,EntitySkeleton.class, 1.0D, true));
            this.goalSelector.a(4, new PathfinderGoalWalktoTile(this, (float) 1.0));
            this.targetSelector.a(1, new PathfinderGoalHurtByTarget(this, true));
            this.targetSelector.a(2, new PathfinderGoalNearestAttackableTarget(this, EntityPig.class, 0, true));
            this.targetSelector.a(3, new PathfinderGoalNearestAttackableTarget(this, EntitySkeleton.class, 0, false));
        }
    }

this is my error

Code:

            this.goalSelector.a(0, new PathfinderGoalFloat(this));

 

Can you give us the error itself?