SpigotCore_Main/src/de/steamwar/entity/REntityServer.java

@@ -137,7 +137,7 @@ public class REntityServer implements Listener {
     void removeEntity(REntity entity) {
         entity.despawn(packet -> updateEntity(entity, packet));
         removeEntityFromChunk(entity);
-        entityMap.put(entity.entityId, entity);
+        entityMap.remove(entity.entityId);
     }
 
     private void addEntityToChunk(REntity entity) {