[fourlastor]

This PR addresses an error that happens with Batteryman Fuel Cell: attempt to index a nil value (local 'tc')

• I am following the contributing guidelines.

The way to reproduce is:

1. Have Batteryman Fuel Cell on P1's field
2. Have another "Batteryman" monster on P1's field, equipped with a spell from P2 (in my case, I noticed it with "Mark of the Rose", but it should be the same for any equip spell)
3. P2's equip spell is the only card on P2's field
4. Use Batteryman Fuel Cell ability: "Once per turn, you can Tribute 1 "Batteryman" monster, except this card, to select 1 card your opponent controls and return it to its owner's hand."
5. The "Batteryman" monster is tributed as the cost, destroying the equipped spell
6. The effect then resolves with no target (tc is nil), and you get the error I mentioned above

[NaimSantos]

This is not the correct fix for this type of problem.

The general if tc check for targets should be reversed for mandatory trigger effects that target, which is a scenario where it is actually possible to a target not be present during the resolution. The if tc part will then prevent further script errors in that effect's resolution.

The correct approach here would be to check if there is a target that is not among the equip group of the card that is about to be used as the cost (because tributing that card will also cause the equip card(s) to leave the field).

Unfortunately, that only works for interactions with equip cards, but it fails in other scenarios, such as cards that have effects like "Destroy this card when that target/it leaves the field" (where "that target/it" = the card that is going to be used as cost.)

[fourlastor]

Thank you for the review, that makes sense. I can address this by changing the activation check instead, do you want me to keep the if so that the script doesn't crash in the cases that aren't covered by the equip check?

[fourlastor]

@NaimSantos I changed the approach, following https://github.com/ProjectIgnis/CardScripts/blob/dc441e0473596531c86820619bacc39f10b2a6f8/official/c68508433.lua (Spirit Tech Force - Pendulum Ruler) which has a similar idea (tribute, then destroy)

return c:IsSetCard(SET_BATTERYMAN) and Duel.IsExistingTarget(Card.IsAbleToHand,tp,0,LOCATION_ONFIELD,1,c:GetEquipGroup()+c)

A batteryman, and a card that can be targeted by the effect, on the field, excluding the equipped cards of that batteryman (as they would be destroyed when tributing)