Explored this problem some more, a sufficient set of conditions are (from weapon_data.csv):
- Chargeup > 0
- Chargedown = 0
- Burst size > 1
- Burst delay > 0
Then I think if the weapon is disabled while firing it can break and no longer be usable even once it is repaired
Example cases where this occurs (chargeup/chargedown/burst size/burst delay):
Kadur Remnant's Volley Driver (0.5/0/8/0.05) and Crystal Resonance Splintergun (0.5/0/7/0.12)
Upgraded Rotary Weapons' edited versions of Storm Needler (0.2/0/9999/0.1) and Ion Pulser (0.1/0/3/0.1)
I don't see any cases where this is an issue in Vanilla, but I reproduced the issue by editing Plasma Cannon from 0.33/1.01/3/0.33 to 0.33/
0/3/0.33.
By the presence of NaN issues and increasing the chargedown for the affected weapons to 0.0001 fixing the issue, the chargedown of 0 is definitely a necessary condition, although I was not able to reproduce it with IR Pulse Laser (0.333333/0/x/x) nor Paladin PD Laser (0/0/0.2/0.1).
Anyways, hopefully this is enough to diagnose what the issue is and the workaround for any potential mods.