From 02fbd4372d6b575d9cb5ede0f291a485018757ed Mon Sep 17 00:00:00 2001
From: Jared Brown <206airmail@gmail.com>
Date: Sun, 24 May 2026 11:09:24 -0800
Subject: [PATCH] Guard spec.loadVolume access in doUpdate to avoid nil-index
 crash

spec.loadVolume is only created in initialiseTransformGroups, which is
called from onLoad only when self.isServer and the vehicle is not in
SHOP_CONFIG. On a multiplayer client, or for vehicles UAL detects as
autoload-capable but that lack a configured loadArea, spec.loadVolume
is therefore nil.

The customOffset/customRotation block in doUpdate dereferences
spec.loadVolume.length unconditionally, producing repeated
"UAL - FATAL ERROR: <vehicle>" log spam via the pcall in
onUpdate/onUpdateTick and permanently disabling UAL on the vehicle.

Wrap the offset/rotation block with `if spec.loadVolume then ... end`.
The action-event update block above is unaffected and continues to run.
---
 UniversalAutoload.lua | 47 ++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/UniversalAutoload.lua b/UniversalAutoload.lua
index a2a40c6..34ed246 100644
--- a/UniversalAutoload.lua
+++ b/UniversalAutoload.lua
@@ -2585,32 +2585,37 @@ function UniversalAutoload:doUpdate(dt, isActiveForInput, isActiveForInputIgnore
 		spec.customOffset = spec.customOffset or 0
 		spec.customRotation = spec.customRotation or 0
 
-		local rotationshift = spec.loadVolume.length / 3
-		local direction = (spec.currentTipside == "right") and 1 or -1
-		local function clampOffset()
-			local minOffset = (spec.customRotation == 0) and 0 or rotationshift
-			local maxOffset = spec.loadVolume.length / 2 + minOffset
-			spec.customOffset = math.clamp(spec.customOffset, minOffset, maxOffset)
-		end
+		-- spec.loadVolume is only populated server-side by initialiseTransformGroups,
+		-- or for vehicles without a valid loadArea config. Skip the shift/rotate logic
+		-- in those cases to avoid "attempt to index nil with 'length'".
+		if spec.loadVolume then
+			local rotationshift = spec.loadVolume.length / 3
+			local direction = (spec.currentTipside == "right") and 1 or -1
+			local function clampOffset()
+				local minOffset = (spec.customRotation == 0) and 0 or rotationshift
+				local maxOffset = spec.loadVolume.length / 2 + minOffset
+				spec.customOffset = math.clamp(spec.customOffset, minOffset, maxOffset)
+			end
 
-		if spec.leftKeyPressed then
-			spec.customOffset = spec.customOffset - (UniversalAutoload.SHIFT_DELTA * direction)
-			clampOffset()
-		end
+			if spec.leftKeyPressed then
+				spec.customOffset = spec.customOffset - (UniversalAutoload.SHIFT_DELTA * direction)
+				clampOffset()
+			end
 
-		if spec.rightKeyPressed then
-			spec.customOffset = spec.customOffset + (UniversalAutoload.SHIFT_DELTA * direction)
-			clampOffset()
-		end
+			if spec.rightKeyPressed then
+				spec.customOffset = spec.customOffset + (UniversalAutoload.SHIFT_DELTA * direction)
+				clampOffset()
+			end
 
-		if spec.rotateKeyPressed then
-			local rotated = spec.customRotation ~= 0
+			if spec.rotateKeyPressed then
+				local rotated = spec.customRotation ~= 0
 
-			spec.customRotation = rotated and 0 or -math.pi / 2
-			spec.customOffset = spec.customOffset + (rotated and -rotationshift or rotationshift)
+				spec.customRotation = rotated and 0 or -math.pi / 2
+				spec.customOffset = spec.customOffset + (rotated and -rotationshift or rotationshift)
 
-			spec.rotateKeyPressed = false
-			clampOffset()
+				spec.rotateKeyPressed = false
+				clampOffset()
+			end
 		end
 
 	end