[Scripting Question] Not sure why new move will not work

[Hypno097]

I am creating a new move called Crasher Kick which is a multi-hit move, hitting 2 times (like bonemerang) however, the first hit is Ground type and the second hit is Fighting type.

PBEffects:

CrasherKick=115

PokeBattle_Battler below "@effects[PBEffects::Yawn] = 0":

@effects[PBEffects::CrasherKick] = false

At around line 2869 in the "def pbProcessMoveAgainstTarget" section:

if thismove.function==0x187 && numhits>1 # Crasher Kick
  user.effects[PBEffects::CrasherKick]=true
end

Pokebattle_MoveEffects:

class PokeBattle_Move_187 < PokeBattle_Move
  def pbIsMultiHit
    return true
  end

  def pbNumHits(attacker)
    return 2
  end

  def pbModifyType(type,attacker,opponent)
    if attacker.effects[PBEffects::CrasherKick]==true
      type=getConst(PBTypes,:FIGHTING)
    end
  end
end

Finally in Pokebattle_Battle in the "End of round" section:

@battlers[i].effects[PBEffects::CrasherKick]=false

I keep getting this error (attachment) whenever i try to use the move and i'm not sure why?