What is this error

Exception: Lua Worker Error:
…ts/shared/functional/COMMON/CCarCalculator_TestTrack.lua:1268: attempt to perform arithmetic on a nil value
Stack Traceback

(1) metamethod C function ‘__sub’
(2) Lua method ‘TestDriveInternal’ at file ‘scripts/shared/functional/COMMON/CCarCalculator_TestTrack.lua:1268’
Local variables:
self = table: 0x0200d956da00 {lastAccessTime:2765.55, SelectedFactory:6, CarInfo:table: 0x02004d48a900 (more…)}
params = table: 0x01ffa15599a0 {1:table: 0x0200d956fb80}
track = table: 0x0200d956fb80 {radius_copy:table: 0x01ffc8d33140, LayoutInfo:table: 0x0200d9562400, corner_coefficient:1 (more…)}
corner_coefficient = number: 1
temp = table: 0x01ffc8d36bc0 {1:0, 2:35, 3:65, 4:97, 5:0, 6:125, 7:0, 8:23, 9:0, 10:42, 11:0, 12:0, 13:0 (more…)}
radii = table: 0x01fff16b3f10 {1:0, 2:20, 3:23, 4:25, 5:28, 6:35, 7:39, 8:42, 9:65, 10:90, 11:97, 12:125 (more…)}
tracklayout = table: 0x01ffc8d39f00 {x:table: 0x01ffc8d35300, T_length:4742.0926547151, phi:table: 0x01ffc8d35200 (more…)}
tmp = nil
T_length = number: 4742.09
dstep = number: 4
dstep2 = number: 4
PDATA = table: 0x01ffc8d36d80 {B:0, phi:0, p1X:82.098531554042, vt_orig:table: 0x0200cd833000, dist:table: 0x0200d93390c0 (more…)}
targetspeed = number: 51.3333
idx = number: 52
ab = table: 0x01ffd2dd9f00 {1:-11.685127629251, 2:-11.687395920476, 3:-11.690962977571, 4:-11.695828967902 (more…)}
vb = table: 0x01ffd2dd0ac0 {1:1, 2:2, 3:3, 4:4, 5:5, 6:6, 7:7, 8:8, 9:9, 10:10, 11:11, 12:12, 13:13 (more…)}
xb = table: 0x01ffd2dd6b00 {1:0.031854939441573, 2:0.15059358393347, 3:0.35449184517589, 4:0.64348103002747 (more…)}
TSpenalty = number: -0.008
num_radii = number: 16
r = table: 0x0200cd83b4c0 {1:0, 2:35, 3:65, 4:97, 5:0, 6:125, 7:0, 8:23, 9:0, 10:42, 11:0, 12:0, 13:0 (more…)}
num_segments = number: 31
dists1 = table: 0x0200cd835040 {1:105, 2:44.595391990836, 3:79.428361874003, 4:250.67219381891, 5:200.0399960008 (more…)}
vcorn = table: 0x0200cd837880 {1:10080, 2:0, 3:0, 4:0, 5:10080, 6:0, 7:10240, 8:0, 9:10320, 10:0, 11:10240 (more…)}
dists = table: 0x0200cd835040 {1:105, 2:44.595391990836, 3:79.428361874003, 4:250.67219381891, 5:200.0399960008 (more…)}
dist1 = table: 0x0200cd830900 {1:0, 2:4, 3:8, 4:12, 5:16, 6:20, 7:24, 8:28, 9:32, 10:36, 11:40, 12:44 (more…)}
gradient = table: 0x0200cd830200 {1:0, 2:0, 3:0, 4:0, 5:0, 6:0, 7:0, 8:0, 9:0, 10:0, 11:0, 12:0, 13:0, 14:0 (more…)}
trackradius = table: 0x0200cd831c40 {1:0, 2:0, 3:0, 4:0, 5:0, 6:0, 7:0, 8:0, 9:0, 10:0, 11:0, 12:0, 13:0, 14:0 (more…)}
s = number: 31
i = number: 1187
sumDists1 = number: 4742.09
res = table: 0x0200cd83fe80 {rpm:table: 0x0200cd83a700, x:table: 0x0200cd83e1c0, ay:table: 0x0200cd83b640 (more…)}
prevtime = number: 0.1
indvc = number: 15
prevdist = number: 29.4153
reference = number: 0
axlimfac = number: 1
ay_targ = number: 0
ay_curr = number: 0
throttletarget = number: 0
speed = number: 51.3333
GearboxRatios = table: 0x0200cd8348c0 {1:3.0135319462684, 2:2.2073895142948, 3:1.5867107291485, 4:1.1942737772477 (more…)}
clutchPart = table: 0x01ffbcfb2d80 {ServiceBase:7500, YearUnlock:1950, TorqueLimit:table: 0x01ffc0855d40, OffroadMulti:1.05 (more…)}
gearDelay = number: 0.24997
deltatime = number: 0.01
(for index) = number: 8.24
(for limit) = number: 1800
(for step) = number: 0.01
t = number: 8.24
cg = table: 0x01ffaa8f7e40 {l_f:0.94689304317403, downForceCG:table: 0x01ffaa8fbac0, downForce:40.729454943544 (more…)}
downForce = nil
downForceCG = nil
(for index) = number: 28
(for limit) = number: 29.4153
(for step) = number: 4
prev = number: 28
(*temporary) = number: 9.41527
(*temporary) = nil
(*temporary) = number: 1.08581e-311
(*temporary) = number: 51
(*temporary) = number: 0
(*temporary) = number: 1.08581e-311
(*temporary) = number: 0
(*temporary) = nil
(*temporary) = number: 1
(*temporary) = number: 0
(*temporary) = number: 1.08585e-311
(*temporary) = number: 0.5
(*temporary) = string: “attempt to perform arithmetic on a nil value”
(3) Lua function ‘?’ at file ‘scripts/ue4/WorkerInit.lua:236’ (best guess)
Local variables:
tasks = table: 0x01ffed49e3e0 {1:56}
(for generator) = C function: next
(for state) = table: 0x01ffed49e3e0 {1:56}
(for control) = userdata: 0x7fff00000002
k = number: 1
v = string: “56”
value = table: 0x01ffbcf29240 {IndexUID:56, TrimUID:CCCDF8534F8877F826182D833D2135AF, ModelUID:7331BA3B401998AFA4378A95A1B561D8 (more…)}
jobs = table: 0x01ffed49e430 {}
success = boolean: true
dump = table: 0x01ffbcf29240 {IndexUID:56, TrimUID:CCCDF8534F8877F826182D833D2135AF, ModelUID:7331BA3B401998AFA4378A95A1B561D8 (more…)}
CarCalculator = table: 0x0200d956da00 {lastAccessTime:2765.55, SelectedFactory:6, CarInfo:table: 0x02004d48a900 (more…)}
EngineCalculator = table: 0x02002f624700 {lastAccessTime:2765.551, SelectedFactory:6, Time:table: 0x0200cb4c41c0 (more…)}
start = number: 2765.56

help please

Two questions for you:

First, when and where does this error occur, apart from in the test track simulation? Second, when you try to clear the error, does it stay cleared or does it come back?