Strange Error upon a person connecting to the server

[GreenEyeGM]

16:36:06 [SEVERE] Dec 24, 2018 4:36:06 PM net.md_5.bungee.event.EventBus post
WARNING: Error dispatching event PreLoginEvent(cancelled=false, cancelReason=null, connection=[Nikolaew] <-> InitialHandler) to listener me.vik1395.BungeeHostLimiter.ListenerClass@f08d676
java.lang.NullPointerException
at me.vik1395.BungeeHostLimiter.ListenerClass.onLogin(ListenerClass.java:28)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at net.md_5.bungee.event.EventHandlerMethod.invoke(EventHandlerMethod.java:19)
at net.md_5.bungee.event.EventBus.post(EventBus.java:46)
at net.md_5.bungee.api.plugin.PluginManager.callEvent(PluginManager.java:377)
at net.md_5.bungee.connection.InitialHandler.handle(InitialHandler.java:372)
at net.md_5.bungee.protocol.packet.LoginRequest.handle(LoginRequest.java:39)
at net.md_5.bungee.netty.HandlerBoss.channelRead(HandlerBoss.java:77)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:276)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:263)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304)
at io.netty.handler.timeout.ReadTimeoutHandler.channelRead(ReadTimeoutHandler.java:152)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:846)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:823)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:339)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:255)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:112)
at java.lang.Thread.run(Thread.java:748)