Hier der Error:
[21:28:58 ERROR]: Could not pass event PlayerInteractEntityEvent to Simple-Casino v1.0
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot.jar:git-PaperSpigot-"4c7641d"]
        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) ~[spigot.jar:git-PaperSpigot-"4c7641d"]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-PaperSpigot-"4c7641d"]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:517) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:502) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:1342) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.PacketPlayInUseEntity.a(SourceFile:52) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.PacketPlayInUseEntity.a(SourceFile:11) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_231]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_231]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:774) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [spigot.jar:git-PaperSpigot-"4c7641d"]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_231]
Caused by: java.lang.NullPointerException
        at de.famoushistory.SimpleCasino.util.InventoryManager.createPlayerInventory(InventoryManager.java:50) ~[?:?]
        at de.famoushistory.SimpleCasino.listeners.VillagerClickListener.handleVillagerClick(VillagerClickListener.java:35) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_231]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_231]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_231]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_231]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:300) ~[spigot.jar:git-PaperSpigot-"4c7641d"]
        ... 16 more


Und hier die Verursachende Zeile:

        slotInventorys.put(p.getUniqueId(), inv);

slotInventory:

	 	private static Map<UUID, Inventory> slotInventorys;