[11:15:21] [Server thread/INFO]: Unknown command. Type "/help" for help.
[11:15:24] [Server thread/INFO]: Freeze_Line lost connection: Disconnected
[11:15:24] [Server thread/ERROR]: Could not pass event PlayerQuitEvent to TheWalls v2.0.1
org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:320) ~[serverengine.jar:git-Spigot-800b93f-8160e29]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[serverengine.jar:git-Spigot-800b93f-8160e29]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:529) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:514) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.PlayerList.disconnect(PlayerList.java:387) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:1370) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.NetworkManager.handleDisconnection(NetworkManager.java:320) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.ServerConnection.c(ServerConnection.java:153) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.b(MinecraftServer.java:1105) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.DedicatedServer.b(DedicatedServer.java:399) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.a(MinecraftServer.java:984) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:824) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_251]
Caused by: java.lang.NullPointerException
        at java.util.concurrent.ConcurrentHashMap.get(Unknown Source) ~[?:1.8.0_251]
        at java.util.concurrent.ConcurrentHashMap.containsKey(Unknown Source) ~[?:1.8.0_251]
        at net.cubecraftgames.walls.PlayerDisconnectListner.OnPlayerDisconnect(PlayerDisconnectListner.java:22) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_251]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_251]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_251]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_251]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:316) ~[serverengine.jar:git-Spigot-800b93f-8160e29]
        ... 12 more
[11:15:24] [Server thread/INFO]: Freeze_Line left the game
[11:15:24] [Server thread/WARN]: [Essentials] Task #1156 for Essentials v2.17.2.0 generated an exception
java.lang.NullPointerException: null
        at com.earth2me.essentials.xmpp.XMPPManager.updatePresence(XMPPManager.java:142) ~[?:?]
        at com.earth2me.essentials.xmpp.EssentialsXMPP.updatePresence(EssentialsXMPP.java:113) ~[?:?]
        at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftTask.run(CraftTask.java:81) ~[serverengine.jar:git-Spigot-800b93f-8160e29]
        at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:394) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.b(MinecraftServer.java:1036) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.DedicatedServer.b(DedicatedServer.java:399) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.a(MinecraftServer.java:984) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:824) [serverengine.jar:git-Spigot-800b93f-8160e29]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_251]