[15:24:41] [Server thread/ERROR]: Exception when acecheesecr14 attempted to tab complete /summon zom
org.bukkit.command.CommandException: Unhandled exception executing tab-completer for 'summon zom' in org.bukkit.craftbukkit.v1_8_R1.command.VanillaCommandWrapper(summon)
        at org.bukkit.command.SimpleCommandMap.tabComplete(SimpleCommandMap.java:217) ~[Spigot:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.CraftServer.tabCompleteCommand(CraftServer.java:1586) [Spigot:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.CraftServer.tabComplete(CraftServer.java:1570) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.tabCompleteCommand(MinecraftServer.java:1116) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:1869) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.PacketPlayInTabComplete.a(SourceFile:46) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.PacketPlayInTabComplete.a(SourceFile:10) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [Spigot:git-Spigot-c3c767f-33d5de3]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_31]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_31]
        at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:696) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:634) [Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:537) [Spigot:git-Spigot-c3c767f-33d5de3]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_31]
Caused by: java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.String
        at net.minecraft.server.v1_8_R1.EntityTypes.b(SourceFile:240) ~[Spigot:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.CommandSummon.tabComplete(SourceFile:125) ~[Spigot:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.command.VanillaCommandWrapper.tabComplete(VanillaCommandWrapper.java:52) ~[Spigot:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.command.SimpleCommandMap.tabComplete(SimpleCommandMap.java:213) ~[Spigot:git-Spigot-c3c767f-33d5de3]
        ... 14 more