Exception on player disconnect/crash when a Dialog window is active

[plsegott]

[SampSharp:ERROR] Unhandled exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.InvalidOperationException: An attempt was made to transition a task to a final state when it had already completed.
   at System.Threading.Tasks.TaskCompletionSource`1.SetResult(TResult result)
   at SampSharp.Entities.SAMP.DialogService.<>c__DisplayClass4_0`1.<Show>g__Handler|0(DialogResult result)
   at SampSharp.Entities.SAMP.DialogSystem.OnPlayerDisconnect(VisibleDialog player, DisconnectReason _)
   at lambda_method59(Closure, Object, Object[], IServiceProvider, IEntityManager)
   at SampSharp.Entities.EventService.<>c__DisplayClass11_0.<CreateInvoker>b__0(Object instance, EventContext eventContext)
   at SampSharp.Entities.EventService.Invoke(EventContext context)
   at SampSharp.Entities.SAMP.PlayerDisconnectMiddleware.Invoke(EventContext context, IEntityManager entityManager)
   at lambda_method68(Closure, Object, EventContext, IServiceProvider)
   at SampSharp.Entities.EcsBuilderUseMiddlewareExtensions.<>c__DisplayClass3_1.<UseMiddleware>b__2(EventContext context)
   at SampSharp.Entities.EventService.<>c__DisplayClass12_0.<BuildInvoke>b__0(Object[] args)
   at InvokeStub_<>c__DisplayClass12_0.<BuildInvoke>b__0(Object, Object, IntPtr*)
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
   --- End of inner exception stack trace ---
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at SampSharp.Core.Callbacks.Callback.Invoke(Byte[] buffer, Int32 startIndex)
   at SampSharp.Core.HostedGameModeClient.PublicCall(String name, IntPtr data, Int32 length)