[15:42:23 ERROR]: Could not pass event InventoryClickEvent to CustomWings v3.0
org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:309) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:485) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.PlayerConnection.a(PlayerConnection.java:2127) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:33) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:10) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.PlayerConnectionUtils.a(SourceFile:10) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_201]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_201]
        at net.minecraft.server.v1_13_R2.SystemUtils.a(SourceFile:199) [spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:895) [spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:417) [spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:830) [spigot.jar:git-Spigot-518206a-a5b9c7b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:728) [spigot.jar:git-Spigot-518206a-a5b9c7b]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_201]
Caused by: java.lang.NullPointerException
        at tigeax.customwings.gui.CWGUIManager.getPlayerHeadItem(CWGUIManager.java:299) ~[?:?]
        at tigeax.customwings.gui.guis.EditorWingSettings.open(EditorWingSettings.java:37) ~[?:?]
        at tigeax.customwings.gui.CWGUIManager.openGUI(CWGUIManager.java:94) ~[?:?]
        at tigeax.customwings.main.CWPlayer.openCWGUI(CWPlayer.java:91) ~[?:?]
        at tigeax.customwings.gui.guis.Editor.click(Editor.java:59) ~[?:?]
        at tigeax.customwings.gui.CWGUIManager.CWGUIClick(CWGUIManager.java:171) ~[?:?]
        at tigeax.customwings.eventlisteners.InventoryClickEventListener.event(InventoryClickEventListener.java:84) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor34.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_201]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[spigot.jar:git-Spigot-518206a-a5b9c7b]
        ... 15 more