So apparently if you are using a warehouse and you go to uncraft stairs in the terminal, it causes a crash. Crash report is here:
crash-2019-09-22_22.43.42-client.txt

The clues I've assembled sofar:
This crash only affects multiplayer.
This only happens when both the base block and stair block are in the warehouse.
Pulling out the stairs and block and putting them back in seems to fix the issue.
The items were initially input from an ender chest, screenshot below.

Let me know any further info you need to figure out the source of the issue!