Wandering Trader exception

[ProjectHSI]

Unknown circumstances or reproduction steps, just found this in the server log.

[22:14:46] [Server thread/ERROR]: Could not pass event InventoryOpenEvent to STEMCraft v1.5
java.lang.IllegalStateException: MerchantRecipe can only have maximum 2 ingredients
        at com.google.common.base.Preconditions.checkState(Preconditions.java:512) ~[guava-32.1.2-jre.jar:?]
        at org.bukkit.inventory.MerchantRecipe.setIngredients(MerchantRecipe.java:117) ~[purpur-api-1.20.4-R0.1-SNAPSHOT.jar:?]
        at com.stemcraft.feature.SMVillagerTrading.lambda$onEnable$0(SMVillagerTrading.java:59) ~[STEMCraft-1.5.jar:?]
        at com.stemcraft.core.event.SMEvent.lambda$register$0(SMEvent.java:27) ~[STEMCraft-1.5.jar:?]
        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:77) ~[purpur-api-1.20.4-R0.1-SNAPSHOT.jar:git-Purpur-2159]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[purpur-api-1.20.4-R0.1-SNAPSHOT.jar:?]
        at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:126) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:617) ~[purpur-api-1.20.4-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_20_R3.event.CraftEventFactory.callInventoryOpenEventWithTitle(CraftEventFactory.java:1438) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.server.level.ServerPlayer.openMenu(ServerPlayer.java:1628) ~[?:?]
        at net.minecraft.world.item.trading.Merchant.openTradingScreen(Merchant.java:41) ~[?:?]
        at net.minecraft.world.entity.npc.Villager.startTrading(Villager.java:454) ~[?:?]
        at net.minecraft.world.entity.npc.Villager.mobInteract(Villager.java:432) ~[?:?]
        at net.minecraft.world.entity.Mob.interact(Mob.java:1383) ~[?:?]
        at net.minecraft.world.entity.player.Player.interactOn(Player.java:1171) ~[?:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl$4.performInteraction(ServerGamePacketListenerImpl.java:2824) ~[?:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl$4.a(ServerGamePacketListenerImpl.java:2844) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundInteractPacket$InteractionAction.dispatch(ServerboundInteractPacket.java:131) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundInteractPacket.dispatch(ServerboundInteractPacket.java:80) ~[?:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl.handleInteract(ServerGamePacketListenerImpl.java:2783) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundInteractPacket.handle(ServerboundInteractPacket.java:67) ~[?:?]
        at net.minecraft.network.protocol.game.ServerboundInteractPacket.handle(ServerboundInteractPacket.java:12) ~[?:?]
        at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:54) ~[?:?]
        at net.minecraft.server.TickTask.run(TickTask.java:18) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:153) ~[?:?]
        at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[?:?]
        at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1498) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:194) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:126) ~[?:?]
        at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1475) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1398) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.util.thread.BlockableEventLoop.runAllTasks(BlockableEventLoop.java:114) ~[?:?]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1590) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1246) ~[purpur-1.20.4.jar:git-Purpur-2159]
        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:323) ~[purpur-1.20.4.jar:git-Purpur-2159]

[nomadjimbob]

Need the code to ensure that only 2 items are being placed in the recipe. I assume that the item cost is causing this, providing more than 2 types of coins