I have created a shop of rockets on my server using active supplier.
When a player put a Diamond in a chest, the supplier connected to the same chest try to fill it with rocket.

The rockets are auto-crafted in the shop with a diamond in satellite slot to act as a payment.
So rocket are given to player only if all ingredient (Here The Diamond) are provided.

Everything work just fine but when the area is unloaded the server crash instantly.

Here is the bug report for this crash that is directly located on the pipe that supply the rockets.
crash-2019-12-14_14.05.11-server.txt

Hope to be clear enough, thanks for this great mod :)

I fix it by moving all the system in the same chunk

A chunkloader could help situations like this. In generic, if a comlex system occupies more than one chunk (either because the placement of your base or the size of the system) I enforce loading it with a chunk loader that covers the whole system. Some mods/machines loads its chunk some of them not.