Happened in pack All The Mods 6 v1.7.7
Mod version: 0.31

A crash happens upon switching a creative importer attached to an empty Dock (from Tank Null) to fluid mode
crash-2021-08-10_10.07.35-server.txt
crash-2021-08-10_10.50.47-server.txt

https://pastebin.com/hvU0trCH (ticking took 60s)
https://pastebin.com/4dfctQLU (Actual error, out of bounds)

934e75c :)