fix cleanup

src/de/steamwar/spectatesystem/PacketProcessor.java

@@ -404,7 +404,7 @@ class PacketProcessor {
         }
 
         if(source.isClosed()){
-            execSync(() -> endSpectating());
+            Bukkit.getScheduler().runTask(SpectateSystem.get(), this::endSpectating);
             task.cancel();
         }
     }