Clicking off screen with kit selection menu causes a index out of bounds exception

[Parsonswy]

java.lang.ArrayIndexOutOfBoundsException: -999
at net.peacefulcraft.trenchpvp.menu.GameMenu$Row.<init>(GameMenu.java:111) ~[?:?]
at net.peacefulcraft.trenchpvp.menu.GameMenu.getRowFromSlot(GameMenu.java:92) ~[?:?]
at net.peacefulcraft.trenchpvp.menu.GameMenu.onInventoryClick(GameMenu.java:74) ~[?:?]
at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor65.execute(Unknown Source) ~[?:?]
at org.bukkit.plugin.EventExecutor.lambda$create$1(EventExecutor.java:69) ~[patched_1.15.2.jar:git-Paper-253]
at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[patched_1.15.2.jar:git-Paper-253]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[patched_1.15.2.jar:git-Paper-253]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:607) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:2369) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.PacketPlayInWindowClick.a(SourceFile:32) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.PacketPlayInWindowClick.a(SourceFile:10) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:23) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.TickTask.run(SourceFile:18) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.MinecraftServer.ba(MinecraftServer.java:1081) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:1074) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:1035) ~[patched_1.15.2.jar:git-Paper-253]
at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:950) ~[patched_1.15.2.jar:git-Paper-253]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]