Forge Version: 1.16.3-34.1.42
Inventory Sorter Version: 1.16.1-18.1.0
No other mods present

Steps to reproduce:

1. Install forge + mod.
2. Create a single player world (unsure if this issue exists in multiplayer)
3. Type /invsorter bladd then press space.
4. Proceed to crash.

Crash report

I noticed the jar name is labeled 1.16.1. Is this version suppose to be compatible with 1.16.3? It's currently marked compatible with 1.16.3 on CurseForge.

Can confirm this as well, happens regardless of if an inventory has been sorted since loading the world or not.