src/de/steamwar/spectatesystem/PacketProcessor.java

@@ -88,7 +88,11 @@ class PacketProcessor {
     private void entityDespawns() throws IOException{
         int entityId = source.rInt();
 
-        Bukkit.getScheduler().runTask(SpectateSystem.get(), () -> REntity.getEntity(entityId).remove());
+        Bukkit.getScheduler().runTask(SpectateSystem.get(), () -> {
+            REntity rEntity = REntity.getEntity(entityId);
+            if (rEntity == null) return;
+            rEntity.remove();
+        });
     }
 
     private void entitySneak() throws IOException {