Issue: Enabling Dual Wield Mode through Mod options throws errors/Crashes save games
Temporary Fix: Load from your most recent Autosave and it should work again.

How I found the issue:
I was tinkering and exploring the Mod options and out of curiosity I turned on 'Dual Wield Mode'
then afterwards I was receiving lots of errors and my game would crash upon loading a save.
You also cannot Disable Dual Wield Mode as the Green check mark won't change.

I still save my games manually alongside the Auto save just to be sure, and the Manual Save got corrupted after I turned on Dual Wield Mode on.

Run and Gun works fine for me without errors, Melee is working fine and Search and Destroy works fine too. I have majority of the Top 50 Mods installed, so no real conflicts I can mention..
Works smooth now.