Its probably tracer code I used isn't intended to work with NPCs, I did these guns mostly as player-only, so I didn't tested how NPCs would use them or any TFA gun honestly, I might later change tracer code based on TFA code and update addon, but I don't remember which tool I need to spawn NPC with any weapon except spawning them with console.

If anything, it only happens when NPCs die while using such weapons, though rarely it happens.

I use the default branch, without any beta branch being used.

Do you use different Garrysmod branch, like dev or something? I can't fix problem which I can't reproduce, I don't get any errors, and all effects works. Maybe later I might use TFA Gauss effect as base, it uses beam too, if this one not works.

Correct me if I'm wring though.

Here's another set, just encountered them earlier, though I'm pretty sure they're similar in some way:
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_blue_tracer/init.lua:9: Tried to use a NULL entity!
1. GetClass - [C]:-1
2. unknown - lua/effects/tfa_c_nybras_blue_tracer/init.lua:9
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_blue_tracer/init.lua:69: bad argument #1 to '__sub' (Vector expected, got nil)
1. __sub - [C]:-1
2. unknown - lua/effects/tfa_c_nybras_blue_tracer/init.lua:69
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_blue_tracer/init.lua:56: attempt to perform arithmetic on field 'FlashA' (a nil value)
1. unknown - lua/effects/tfa_c_nybras_blue_tracer/init.lua:56

Got some errors when using this weapon, this gun is awesome otherwise:
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_ion_tracer/init.lua:9: Tried to use a NULL entity!
1. GetClass - [C]:-1
2. unknown - lua/effects/tfa_c_nybras_ion_tracer/init.lua:9
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_ion_tracer/init.lua:69: bad argument #1 to '__sub' (Vector expected, got nil)
1. __sub - [C]:-1
2. unknown - lua/effects/tfa_c_nybras_ion_tracer/init.lua:69
[[TFA] Nybras Laser Rifle] lua/effects/tfa_c_nybras_ion_tracer/init.lua:56: attempt to perform arithmetic on field 'FlashA' (a nil value)
1. unknown - lua/effects/tfa_c_nybras_ion_tracer/init.lua:56

Вижу круто продолжай в том же духе