[13:51:42 ERROR]: Could not pass event SpawnerDropEvent to SpawnerUpgrades v1.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at com.bgsoftware.wildstacker.hooks.SpawnersProvider_SilkSpawners.dropOrGiveItem(SpawnersProvider_SilkSpawners.java:115) [WildStacker-3.0.1.jar:?]
        at com.bgsoftware.wildstacker.handlers.ProvidersHandler.dropOrGiveItem(ProvidersHandler.java:213) [WildStacker-3.0.1.jar:?]
        at com.bgsoftware.wildstacker.listeners.SpawnersListener.onBlockBreak(SpawnersListener.java:254) [WildStacker-3.0.1.jar:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_222]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_222]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_222]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_222]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerInteractManager.breakBlock(PlayerInteractManager.java:286) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerInteractManager.a(PlayerInteractManager.java:215) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:637) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:40) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:10) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_222]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_222]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222]
Caused by: java.lang.NullPointerException: Name is null
        at java.lang.Enum.valueOf(Enum.java:236) ~[?:1.8.0_222]
        at org.bukkit.Material.valueOf(Material.java:1) ~[spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        at hassan.plugin.com.Main.getItemFromLevel(Main.java:158) ~[?:?]
        at hassan.plugin.com.spawneritem.SpawnerItem.createSpawner(SpawnerItem.java:47) ~[?:?]
        at hassan.plugin.com.events.SpawnerEvents.onSpawnerDropEvent(SpawnerEvents.java:338) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_222]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_222]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_222]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_222]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigotmc-1.8.8-R0.1.jar:git-Spigot-e4d4710-e1ebe52]
        ... 28 more