On x86-64, a not-found model path to ents.CreateClientProp(model) causes a crash because error.mdl can't be loaded

[marchc1]

Details

• The addon in question, https://github.com/dvdvideo1234/TrackAssemblyTool or https://steamcommunity.com/sharedfiles/filedetails/?id=287012681, has not been updated since January of 2024.
• All individuals experiencing the crash are on the x86-64 branch of Garry's Mod, and joined two different servers that both had Track Assembly installed. Joining on other betas of the game did not cause crashes (DEV or NONE).
• The problems started March 10th, 2024 with one individual, but two others began experiencing issues the day of the latest release of Garry's Mod (March 13th).
• The error complains that "Model models/ron/plarail/scenery/aj01.mdl not found and models/error.mdl couldn't be loaded". It's a hard-crash Engine Error.
• A whereis for models/error.mdl before joining and crashing results in the expected VPK (garrysmod\sourceengine\hl2_misc.vpk\models\error.mdl).
• The whereis for the aj01.mdl model says the model cannot be found, both on non-crashing and crashing clients.
• The addon aj01.mdl should come from(?), Plarail Advance (https://steamcommunity.com/sharedfiles/filedetails/?id=1512053748), is not installed on either of the servers causing issues, and none of the clients are subscribed to this addon.
• I've seen reports of this issue since late 2021 via searching various places, but only recently have heard of it happening via friends crashing.
• I isolated it to this addon by having one of the friends affected join the server with the addon installed, crash, then join with no other changes other than the addon removed from the server, and no longer experiencing crashes.
• All clients are Windows with NVIDIA GPU's, both the ones that crash and don't crash. Both servers that the players join run on Windows.
• Tried to have one of the people affected subscribe to the addon, did not resolve the issue.
• Tried to switch from "Do not download custom sounds" to "Allow all custom files from server", did not resolve the issue.

Lua trace from one of the crashes:

Executable: C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\bin\win64\gmod.exe

-Lua Stack Traces-
==================
  Client
    0. SetModel - [C]:-1
      1. MakeEntityNone - lua/trackassembly/trackasmlib.lua:2103
        2. GetTransformOA - lua/trackassembly/trackasmlib.lua:2199
          3. RegisterPOA - lua/trackassembly/trackasmlib.lua:2236
            4. (null) - lua/autorun/trackassembly_init.lua:1686
              5. pcall - [C]:-1
                6. Record - lua/trackassembly/trackasmlib.lua:2964
                  7. ImportDSV - lua/trackassembly/trackasmlib.lua:3507
                    8. ProcessDSV - lua/trackassembly/trackasmlib.lua:3771
                      9. (null) - lua/weapons/gmod_tool/stools/trackassembly.lua:95
                        10. include - [C]:-1
                          11. (null) - gamemodes/sandbox/entities/weapons/gmod_tool/stool.lua:154
                            12. include - [C]:-1
                              13. (null) - gamemodes/sandbox/entities/weapons/gmod_tool/shared.lua:372
                                14. include - [C]:-1
                                  15. (null) - gamemodes/sandbox/entities/weapons/gmod_tool/cl_init.lua:11

  Server
    Lua Interface = NULL

  MenuSystem
    *Not in Lua call OR Lua has panicked*

I currently don't have a solid way to reproduce the problem and am using this to store the information somewhere organized. I'll update it as I get more info

[marchc1]

I finally have a way to replicate this:

• Place the contents of this ZIP into your data folder. trackassembly_broken.zip
• Start the game on the x86-64 beta
• Join a server/start a game with Track Assembly installed
• Crash

[marchc1]

Specifically, I crash when only having data/trackassembly/dsv/plarailtrackassembly_pieces.txt present, along with data/trackassembly/set/trackasmlib_dsv.txt

[marchc1]

I think I've isolated the issue down to ents.CreateClientProp, because a simple

local c_Model = ents.CreateClientProp("models/this/isnt/going/to/load.mdl")

causes a crash.

[marchc1]

On the NONE branch, this happens instead

Seems to be purely an issue with x86-64, as both 32-bit and 64-bit will crash

[marchc1]

For some reason, running ClientsideModel on an invalid path not only doesnt crash, but also causes ents.CreateClientProp calls with invalid paths to stop crashing as well?

[marchc1]

Couple of other things to note, just summarizing from the development chat:

• Running local c_Model = ents.CreateClientProp("models/error.mdl") does not cause a crash, but does not stop crashes from occuring later with invalid model paths to this function
• Valid effect paths loaded via ents.CreateClientProp will spew a warning: C_PhysPropClientside::Initialize: PhysModelParseSolid failed for model 'models/props_lab/corkboard002.mdl' @ index 409..
• Replacing models/error.mdl with a different model renamed to error.* (I just copied all the files for hunter/plates/plate05) prevents the crash upon running this function, however, removing error.phy brings it back
• No other method of "preloading" error.mdl fixes this issue other than ClientsideModel on an invalid path, which seems to prevent the issue. I've tried both spawning error.mdl as an effect from the spawnmenu, and using dupes from the workshop with missing models.

[robotboy655]

It should be fixed now, thanks for all the details & work you did there.

[dvdvideo1234]

Optimized on my side also @marchc1 https://github.com/dvdvideo1234/TrackAssemblyTool/commit/f42bdcfde3a7b8a843b1e4a4deea9660a0a1103c