badger: fix logic for checking if an event id exists.

badger/delete.go

@@ -19,6 +19,7 @@ func (b *BadgerBackend) DeleteEvent(ctx context.Context, evt *nostr.Event) error
 		// query event by id to get its idx
 		id, _ := hex.DecodeString(evt.ID)
 		prefix := make([]byte, 1+32)
+		prefix[0] = indexIdPrefix
 		copy(prefix[1:], id)
 		opts := badger.DefaultIteratorOptions
 		opts.PrefetchValues = false