[Error] help me

this is the error
Script'PokeBattle_MoveEffects' line 1743 : LocalJumpError occurred.

unexpected return

this is the Script

################################################################################
# Decreases the target's Attack by 1 stage.(Growl)
################################################################################
class PokeBattle_Move_042 < PokeBattle_Move
def pbEffect(attacker,opponent,hitnum=0,alltargets=nil,showanimation=true)
return super(attacker,opponent,hitnum,alltargets,showanimation) if pbIsDamaging?
return -1 if !opponent.pbCanReduceStatStage?(PBStats::ATTACK,attacker,true,self)
pbShowAnimation(@id,attacker,opponent,hitnum,alltargets,showanimation)
ret=opponent.pbReduceStat(PBStats::ATTACK,1,attacker,false,self)
return ret ? 0 : -1
end

def pbAdditionalEffect(attacker,opponent)
return if opponent.damagestate.substitute
if opponent.pbCanReduceStatStage?(PBStats::ATTACK,attacker,false,self)
opponent.pbReduceStat(PBStats::ATTACK,1,attacker,false,self)
end
end
end