Minecraft CurseForge

I've been setting up my own modded server and this error keeps coming up when someone joins.

[23:05:03] [Server thread/WARN] [minecraft/NetworkSystem]: Failed to handle packet for /192.168.1.119:60453
java.lang.NullPointerException: null
at com.github.ipixeli.gender.settings.PSObj.<init>(PSObj.java:15) ~[PSObj.class:?]
at com.github.ipixeli.gender.settings.SettingsKeeperBase.getOrCreate(SettingsKeeperBase.java:40) ~[SettingsKeeperBase.class:?]
at com.github.ipixeli.gender.common.EventHandler.onPlayerLogin(EventHandler.java:83) ~[EventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_311_EventHandler_onPlayerLogin_PlayerLoggedInEvent.invoke(.dynamic) ~[?:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182) ~[EventBus.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.firePlayerLoggedIn(FMLCommonHandler.java:575) ~[FMLCommonHandler.class:?]
at net.minecraft.server.management.PlayerList.initializeConnectionToPlayer(PlayerList.java:219) ~[pl.class:?]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.completeServerSideConnection(NetworkDispatcher.java:255) ~[NetworkDispatcher.class:?]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.access$100(NetworkDispatcher.java:72) ~[NetworkDispatcher.class:?]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1.func_73660_a(NetworkDispatcher.java:205) ~[NetworkDispatcher$1.class:?]
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:285) ~[gw.class:?]
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:180) [oz.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:790) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) [nz.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_201]
[23:05:03] [Server thread/INFO] [minecraft/NetHandlerPlayServer]: Fevomore lost connection: Internal server error
[23:05:03] [Server thread/INFO] [minecraft/DedicatedServer]: Fevomore left the game