Freshly crafted /dank/nulls are created with no NBT tags. When the player attempts to place a /dank/null on a docking station the mod first marks the station as having a /dank/null docked, and then searches the NBT to find the /dank/null's current inventory.

This happens before the /dank/null is removed from the player's inventory. Currently, if the mod fails to find the appropriate tag on said /dank/null, the interaction silently fails. The /dank/null is not removed from the player's inventory, but it remains on the docking station with no model. This allows for infinite duplication of /dank/nulls that have never had items placed in them.

https://paste.dimdev.org/cuqigewuye.mccrash

Thanks to your realization that it's problem with missing NBT, I was able to make a workaround recipe script using CraftTweaker. For those interested, here it is:
fix dank.zs.txt (just remember to change the file extension back to zs. I had to make it .txt in order to upload it here)

Fixed by #263