Related issue: Tschipp/CarryOn#369

Carry on calls the BlockEntity#load function on the server side, which then classloads BonsaiPotBlockEntity.
BonsaiPotBlockEntity imports ClientLevel here: https://github.com/thraaawn/BonsaiTrees/blob/1.18.1/src/main/java/com/davenonymous/bonsaitrees3/blocks/BonsaiPotBlockEntity.java#L14

Instead of checking for ClientLevel, do level.isClientSide instead.
I will add safeguards on carry on's side to prevent duplication of carried blocks.

This should be fixed in the latest versions for 1.18.2, 1.19.2 and 1.20.1.
If you wouldn't mind retesting, that'd be very much appreciated.