Dank Null Version: 1.12.2-1.6.79.jar
p455w0rds Lib Version: 1.12.2-2.2.156
Forge Version: Not sure how to check (using FTB Revelation mod pack 3.2.0)

Steps To Reproduce:

1. Load two items into dank null
2. Attempt to switch selected items from one to another
3. Input will lag and client will crash

Was this tested on Single Player or Server (or Both)?

Tested on server. I reverted to 1.6.77 to fix. the 1.6.79 upgrade was related to #202 trying to fix the voiding issue.

Was this tested with just Dank Null installed, if not what is the minimal set of mods to cause the issue?

not yet but can try later.