Error deleting 1 item from list

I have the following blocks below within a Notifier.
The problem that is happening is that when executed, whether it is in the Kodular simulator or not, the last FirebaseDB process generates an error and only the first and second Firedbase1 are executed successfully.
But if I remove the first Firedbase1, or the third while keeping the middle one, the failure doesn’t occur. I wonder why this happens? I can not run in the same routine 2 Firedbase?erro1 Erro2

erro4 erro5 erro6

The error tells you that the list retrieved from firebase is empty.
But we do not know how you are retrieving data from firebase.

Tell me what you need me to post here the images

So, but if I disable the first firedbase leaving only the last 2 it doesn’t happen, or if I disable the last one and leave the first two also the error doesn’t happen

So, see, not the error, only the error happens if I leave the firedbase 3



Please while sending blocks set languy to english temporary
Because therr is problem getting this