[08:23:00] [Server thread/WARN]: [MobStacker] Task #119122 for MobStacker v1.4 generated an exception
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at java.util.ArrayList.rangeCheck(ArrayList.java:653) ~[?:1.8.0_65]
    at java.util.ArrayList.get(ArrayList.java:429) ~[?:1.8.0_65]
    at java.util.Collections$UnmodifiableList.get(Collections.java:1309) ~[?:1.8.0_65]
    at com.kiwifisher.mobstacker.StackUtils.stackEntities(StackUtils.java:106) ~[?:?]
    at com.kiwifisher.mobstacker.StackUtils$1.run(StackUtils.java:48) ~[?:?]
    at org.bukkit.craftbukkit.v1_7_R4.scheduler.CraftTask.run(CraftTask.java:71) ~[sv.jar:git-Spigot-1649]
    at org.bukkit.craftbukkit.v1_7_R4.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [sv.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:641) [sv.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:289) [sv.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [sv.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [sv.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [sv.jar:git-Spigot-1649]