Guard spec.loadVolume access in doUpdate to avoid nil-index crash

[206airmail]

Problem

doUpdate crashes for vehicles where spec.loadVolume is nil — either on a multiplayer client (where initialiseTransformGroups never runs because it's gated on self.isServer) or for vehicles UAL detects as autoload-capable but that lack a configured loadArea. The pcall in onUpdate / onUpdateTick catches it, prints UAL - FATAL ERROR: <vehicle> once, and permanently disables UAL on that vehicle for the rest of the session.

Example log entries:

UAL - FATAL ERROR: TRAIL_KING Trailking 70HDG
UniversalAutoload.lua:2588: attempt to index nil with 'length'
UAL - FATAL ERROR: Phiber Tote Deck
UniversalAutoload.lua:2588: attempt to index nil with 'length'

Root cause

spec.loadVolume is only created in initialiseTransformGroups, called from onLoad only when:

if self.isServer and self.propertyState ~= VehiclePropertyState.SHOP_CONFIG then
    ...
    UniversalAutoload.initialiseTransformGroups(self)
end

So on a multiplayer client spec.loadVolume is always nil; on the server it's also nil whenever a vehicle has no valid loadArea config. The customOffset/customRotation block in doUpdate dereferences spec.loadVolume.length unconditionally (lines 2588 and 2592), hence the crash.

Fix

Wrap the offset/rotation block with if spec.loadVolume then ... end. The action-event update block above it (toggle loading, cycle material, etc.) does not depend on loadVolume and continues to run. No behavior change for vehicles where loadVolume is correctly populated.

[loki79uk]

I'm away from home so I can't look until later in the week, but we should identify why the loading volume object was used by the client. Guarding access is a sticking plaster rather than a fix.

[206airmail]

Good catch — diving in further, the loadVolume access is a symptom of a deeper MP issue rather than the bug itself.

Tracing the customOffset/customRotation feature end-to-end:

1. Input — keyDown_left/right/rotate (UniversalAutoload.lua:838–857) set spec.leftKeyPressed etc. on the input-controlling client.
2. Update — the block at UniversalAutoload.lua:2585–2615 (inside if self.isClient and ... isActiveForInputIgnoreSelection) reads those flags and mutates spec.customOffset / spec.customRotation, clamping with spec.loadVolume.length.
3. Consumer — buildObjectsToUnloadTable (UniversalAutoload.lua:3667–3672) reads spec.customOffset / spec.customRotation and applies them via setTranslation(spec.unloadGroup, …). That function is only called from startUnloading, gated by if self.isServer (UniversalAutoload.lua:1239).

No event ever syncs customOffset / customRotation from client to server. I grepped the whole repo including events/ — nothing. So in MP:

• On a non-host client, the update block crashes on the first input tick (the bug this PR papers over), because initialiseTransformGroups only runs server-side, leaving spec.loadVolume == nil on every client.
• Even if it didn't crash, the mutations would only ever live on the client and never reach the server, so the unload-position adjust feature is effectively non-functional in MP today.

(Worth noting up front: this is all about the runtime spec.loadVolume struct built by initialiseTransformGroups. The shop-editor spec.loadingVolume LoadingVolume instance is a separate object, lives only during shop config, and isn't touched by any of this — so the options below don't affect the in-shop autoload zone editor.)

So the real fix is one of:

1. Make the adjustment server-side. Change the doUpdate block from if self.isClient to if self.isServer (it already runs in SP because server == client there), and forward the key state from client to server via a new event — e.g. SetUnloadAdjustEvent that fires from the keyDown handlers carrying {leftKeyPressed, rightKeyPressed, rotateKeyPressed}. Server applies the update against its own loadVolume. Cleanest, but adds an event and event handler.
2. Keep client-side responsiveness, sync values back to server. Sync loadVolume.width/height/length in onReadStream/onWriteStream so the client has bounds, and add a SetUnloadOffsetEvent fired when customOffset / customRotation change. (Only the runtime loadVolume dimensions — the shop loadingVolume is unaffected.) More wire traffic, but lets the client see live feedback if you add any UI later.
3. Skip in MP for now, leave a TODO. Keep my guard but mark the feature as SP-only until the sync is built out.

Happy to do whichever direction you prefer when you're back — option 1 feels right to me. The guard in this PR keeps logs clean in the meantime without changing functional behavior (it's already a no-op on MP clients).

[loki79uk]

Okay ChatGPT.

[206airmail]

Yes, your not wrong..... I only have so much time in life to devote to hobbies, and while i wish i had the time to properly learn coding i have more important IRL things that take up my time. I'm just trying to help solve an issue on a really cool mod!

[loki79uk]

No problem, just reporting the issue is good enough, but I appreciate the extra effort :D

Should be fixed now in https://github.com/loki79uk/FS25_UniversalAutoload/releases/tag/v1.0.2.8

Please test and let me know.

[206airmail]

I was gone for a couple days, i'll test it in a bit.