Here's a link[i.imgur.com] to the image of the in-game GMod problems tab

do you happen to play in singleplater or multiplayer, and does that happen often? just when you start a game, or in some other circumstances?

I was in a single player game and the error happened whenever I even hovered over a rag doll with the tool, not even just when attempting to interact with one. I reloaded the game on multiple different maps and tried out different rag dolls from separate games and the bug persisted. It may have something to do with the fact that I’m running on the 86x-64x branch of GMod.

hm, would it be possible to check if there's no issue on the usual gmod branch, or that would break some other stuff? just need to check if it is indeed the 64 branch that's being weird. perhaps serverside hooks are being fired before player entity is properly in-game, or hooks don't get activated at all.

It's the strangest thing, actually. I booted it up again today and there are no LUA errors but the rotation and movement gizmos don't render. They still are operational (if you can somehow find and click the invisible disk) but simply don't show up.

I may have found the culprit. Ragdoll Mover seems to conflict with the TFA Base, CW 2.0, and FA:S 2.0 addons; especially when you modify those addons' HUD settings. I simply disabled those and the problem is no longer a problem. However, I have used these addons all together before and encountered no such problems, but there's not much you can do about it I guess.

perhaps their HUD draw thing interferes with tool's one, although do their HUDs still work when you don't even have the weapons on your player?

The HUDs for the other addons are weapon-specific, but the ragdoll mover gizmos still did not draw even when I didn't have a weapon in my inventory. The LUA errors began happening once I spawned a weapon into my inventory and continued even after I dropped it/died.

hm, i tried using ragdoll mover with some of the TFA weapons i had, although the only thing that threw a lua error was advanced colour tool, and my gizmos still were around, although i didn't mess with its HUD settings if it had any. you were still using 64x branch, right?

That's right. What I did was turn the HUDs off in the options of the addon so I could use green screen with it. Try that maybe?