[Error] Eerie Impulse

Well, I've tried several things to solve this error that does not break the game. But unsuccessfully so far. It turns out that when using the Eerie Impulse move, the following error appears:

[Pokémon Essentials version 17.1]
Exception: NoMethodError
Message: undefined method `pbCanReduceStatStage?' for nil:NilClass
PokeBattle_MoveEffects:659:in `pbEffect'
PokeBattle_Battler:4404:in `pbUseMove'
PokeBattle_Battler:4403:in `logonerr'
PokeBattle_Battler:4403:in `pbUseMove'
PokeBattle_Battler:4678:in `pbProcessTurn'
PokeBattle_Battler:4677:in `logonerr'
PokeBattle_Battler:4677:in `pbProcessTurn'
PokeBattle_Battle:3402:in `pbAttackPhase'
PokeBattle_Battle:3399:in `each'
PokeBattle_Battle:3399:in `pbAttackPhase'

Click to expand...

I also saw that in essentials there are other moves with the same "pbCanReduceStatStage?" code, but these others work perfectly.

Could someone help me with this?

I'm not sure if this will fix your issue, but it is worth a try:
Update your Pokemon Essentials version to 17.2; those updates contain important bug fixes, which may solve your problem and some future ones.



Edit: The issue is not caused by Essentials.

The problem is within the moves.txt file, correct it to this:
570,EERIEIMPULSE,Eerie Impulse,13D,0,ELECTRIC,Status,100,15,0,00,0,bc,"The user's body generates an eerie impulse. Exposing the target to it harshly lowers the target's Sp. Atk stat."

P.S.
I believe there is also an issue with Relic Song as well, correct it to this:
286,RELICSONG,Relic Song,003,75,NORMAL,Special,100,10,10,04,0,befk,"An ancient song appeals to the hearts of those listening. It may also induce sleep."

Let me know if that fixes your problem! :)