NPE

[Paul2708]

The following error occurs multiple times:

backend_1   | [Connector-Scheduler-7ea9e1e2-1] WARN io.javalin.Javalin - Uncaught exception in WebSocket handler
backend_1   | java.lang.NullPointerException
backend_1   |   at de.paul2708.server.user.User.hasSameSocket(User.java:33)
backend_1   |   at de.paul2708.server.user.UserRegistry.lambda$findUser$0(UserRegistry.java:27)
backend_1   |   at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:176)
backend_1   |   at java.base/java.util.HashMap$ValueSpliterator.tryAdvance(HashMap.java:1696)
backend_1   |   at java.base/java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:127)
backend_1   |   at java.base/java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:502)
backend_1   |   at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:488)
backend_1   |   at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
backend_1   |   at java.base/java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:150)
backend_1   |   at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
backend_1   |   at java.base/java.util.stream.ReferencePipeline.findAny(ReferencePipeline.java:548)
backend_1   |   at de.paul2708.server.user.UserRegistry.findUser(UserRegistry.java:28)
backend_1   |   at de.paul2708.server.ws.event.CloseListener.handle(CloseListener.java:25)
backend_1   |   at io.javalin.websocket.WsHandlerController$onClose$1.invoke(WsHandlerController.kt:56)
backend_1   |   at io.javalin.websocket.WsHandlerController$onClose$1.invoke(WsHandlerController.kt:24)
backend_1   |   at io.javalin.websocket.WsHandlerController.tryBeforeAndEndpointHandlers(WsHandlerController.kt:74)
backend_1   |   at io.javalin.websocket.WsHandlerController.onClose(WsHandlerController.kt:56)
backend_1   |   at jdk.internal.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
backend_1   |   at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
backend_1   |   at java.base/java.lang.reflect.Method.invoke(Method.java:566)
backend_1   |   at org.eclipse.jetty.websocket.common.events.annotated.CallableMethod.call(CallableMethod.java:70)
backend_1   |   at org.eclipse.jetty.websocket.common.events.annotated.OptionalSessionCallableMethod.call(OptionalSessionCallableMethod.java:68)
backend_1   |   at org.eclipse.jetty.websocket.common.events.JettyAnnotatedEventDriver.onClose(JettyAnnotatedEventDriver.java:146)
backend_1   |   at org.eclipse.jetty.websocket.common.WebSocketSession.callApplicationOnClose(WebSocketSession.java:393)
backend_1   |   at org.eclipse.jetty.websocket.common.io.AbstractWebSocketConnection.close(AbstractWebSocketConnection.java:225)
backend_1   |   at org.eclipse.jetty.websocket.common.io.AbstractWebSocketConnection.onReadTimeout(AbstractWebSocketConnection.java:564)
backend_1   |   at org.eclipse.jetty.io.AbstractConnection.onFillInterestedFailed(AbstractConnection.java:172)
backend_1   |   at org.eclipse.jetty.websocket.common.io.AbstractWebSocketConnection.onFillInterestedFailed(AbstractWebSocketConnection.java:539)
backend_1   |   at org.eclipse.jetty.io.AbstractConnection$ReadCallback.failed(AbstractConnection.java:317)
backend_1   |   at org.eclipse.jetty.io.FillInterest.onFail(FillInterest.java:140)
backend_1   |   at org.eclipse.jetty.io.AbstractEndPoint.onIdleExpired(AbstractEndPoint.java:407)
backend_1   |   at org.eclipse.jetty.io.IdleTimeout.checkIdleTimeout(IdleTimeout.java:171)
backend_1   |   at org.eclipse.jetty.io.IdleTimeout.idleCheck(IdleTimeout.java:113)
backend_1   |   at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
backend_1   |   at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
backend_1   |   at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
backend_1   |   at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
backend_1   |   at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
backend_1   |   at java.base/java.lang.Thread.run(Thread.java:834)