Describe the bug
Placing a controller plus any number of supporting blocks without a tank block present in the structure still allows the player access to the tank GUI. If you open the GUI and attempt to insert fluid into the structure, the item you place in the GUI (bucket, tank, whatever) is completely consumed and not returned in the output slot. IMO this could be resolved in two ways:

1. Simply return the item as-is without draining/voiding fluid instead of silently destroying it

2. Do not allow the player access to the tank GUI until the multiblock is properly formed.

Configuration
Mod version: 1.3.0
Forge version: 35.1.13
Minecraft version: 1.16.4
Are you playing on server?: yes

To Reproduce
Steps to reproduce the behavior:
Place a controller plus any number of supporting blocks without a tank block present in the structure. Insert a bucket of any fluid. The bucket and fluid are consumed, returning nothing to the player.

Expected behavior
Either the GUI is not available for unformed multiblocks or the bucket is returned as-is.