Event error on player leave from proxy

[NathanAdhitya]

[16:55:27 WARN]: Error dispatching event ServerDisconnectEvent(player=playername, target=BungeeServerInfo(name=censoredname, socketAddress=/172.18.0.1:5004, restricted=false)) to listener com.triassic.returnme.listeners.PlayerServerChangeListener@cd5ff55
java.lang.NullPointerException: Cannot invoke "net.md_5.bungee.api.connection.Server.getInfo()" because the return value of "net.md_5.bungee.api.connection.ProxiedPlayer.getServer()" is null
        at com.triassic.returnme.listeners.PlayerServerChangeListener.onPlayerLeave(PlayerServerChangeListener.java:20) ~[?:?]
        at jdk.internal.reflect.GeneratedMethodAccessor41.invoke(Unknown Source) ~[?:?]
        at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
        at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?]
        at net.md_5.bungee.event.EventHandlerMethod.invoke(EventHandlerMethod.java:19) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at net.md_5.bungee.event.EventBus.post(EventBus.java:50) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at net.md_5.bungee.api.plugin.PluginManager.callEvent(PluginManager.java:467) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at net.md_5.bungee.connection.DownstreamBridge.disconnected(DownstreamBridge.java:140) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at net.md_5.bungee.netty.HandlerBoss.channelInactive(HandlerBoss.java:60) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:305) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:274) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:81) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.handler.timeout.IdleStateHandler.channelInactive(IdleStateHandler.java:277) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:303) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:274) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.handler.codec.ByteToMessageDecoder.channelInputClosed(ByteToMessageDecoder.java:411) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:376) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:305) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:274) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelInactive(DefaultChannelPipeline.java:1405) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:301) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:901) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.AbstractChannel$AbstractUnsafe$7.run(AbstractChannel.java:813) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:174) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:167) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:403) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[waterfall.jar:git:Waterfall-Bootstrap:1.20-R0.1-SNAPSHOT:ec41547:536]
        at java.lang.Thread.run(Thread.java:833) [?:?]

Hello, I'm getting such errors when a player leaves the proxy. I use Waterfall as my proxy. I believe null checks may be needed to prevent such thing from happening? Thank you.