Greetings

Thx for taking the time to create this mod.

FYI: Playing with PY mods.
Used to work but now I get:

Failed to load mods: pypostprocessing/data-updates.lua:13: attempt to index field '?' (a nil value)
stack traceback:
pypostprocessing/data-updates.lua:13: in function 'set_underground_recipe'
pypostprocessing/data-updates.lua:36: in main chunk

Might be other mods causing the issue but only with fCPU active do I get the error.

Regards

Regards

Thank you for report.
The error tells that the issue is not in fCPU.
Anyway can you provide your modlist?

Ok, as I thought must be something in the PY set that is causing the issue.

Here is the mod list - quite a bit

MODSET:
{
["144-Slot-Wagons"] = "1.0.3",
["5dim-cats"] = "2.0.4",
["5dim_compatibility"] = "2.0.3",
["5dim_core"] = "2.0.39",
["5dim_module"] = "2.0.8",
["5dim_resources"] = "2.0.5",
["5dim_storage"] = "2.0.3",
["5dim_trains"] = "2.0.2",
["7seg"] = "2.0.1",
["Accessible-Signal-Icons"] = "2.0.0",
["Adjustable-Inventory-Size"] = "2.2.0",
["Advanced-Electric-Revamped-v16"] = "0.7.6",
Asteroid_Mining = "2.0.16",
AutoDeconstruct = "1.0.10",
Automatic_Train_Painter = "2.0.1",
BarrelFluidIcons = "1.1.1",
BaseModLibrary2 = "2.0.2",
["Better-Energy-production"] = "0.6.2",
BigAccumulator = "1.0.3",
BigLight = "0.3.0",
CarLogistics = "1.0.1",
ChangeInserterDropLane = "1.2.0",
["CircuitHUD-V2"] = "2.5.1",
CleanedConcrete = "2.0.0",
["Common-Industries"] = "1.0.2",
ConstructionPlannerContinued = "5.1.1",
["Constructron-Continued"] = "2.0.39",
["Cybersyn-Content-Reader"] = "1.0.2",
DeadlockLargerLamp_goakupdate = "0.0.4",
DeadlockStackingForVanilla = "2.0.3",
DeadlocksStackingForPyanadon = "0.6.7",
DiscoScience = "2.0.1",
DisplayPlatesForked = "1.6.1",
EditorExtensions = "2.5.2",
EnhancedCircuitNetworkVisibility = "2.0.0",
EvenDistributionLite = "1.4.5",
FNEI = "0.4.6",
FastGate = "1.1.0",
FilterChests = "1.2.0",
["Flow Control"] = "3.2.3",
["Fluid-level-indicator"] = "0.9.9",
FluidMustFlow = "1.4.4",
FluidWagonColorMask = "2.0.0",
GUI_Unifyer = "2.0.1",
GhostScanner4 = "4.0.6",
["Inventory Sensor"] = "2.0.6",
K1_Advanced_fluid_continued = "2.0.1",
K1_Advanced_storage_continued = "2.0.3",
KS_Power = "2.0.0",
Krastorio2Assets = "2.0.4",
["Kux-BlueprintExtensions"] = "3.3.16",
["Kux-CoreLib"] = "3.17.8",
MaxRateCalculator = "200.0.53",
Milestones = "1.4.7",
Mining_Drones = "2.0.2",
ModuleInserterEx = "7.3.2",
MoreStorageTanksFixed = "2.0.0",
["Nuclear Fuel"] = "1.2.5",
["PipeVisualizer-Updated"] = "2.4.4",
RailSignalPlanner = "2.0.3",
RateCalculator = "3.3.7",
RealisticOres = "9.200.1",
RecipeBook = "4.0.8",
SchallCircuitGroup = "2.0.1",
SchallCircuitScaling = "2.0.0",
SchallLampContrast = "2.0.1",
SchallRemainsPickup = "2.0.2",
SchallTransportGroup = "2.0.2",
SchallVirtualSignal = "2.0.0",
["Solar-Lamp"] = "0.2.1",
["Sort-All-Inventories"] = "1.0.0",
Tapeline = "3.0.4",
TjSignBoards = "1.200.4",
UltimateBeltsSpaceAge = "1.3.0",
UndergroundIndicatorsFixed = "1.3.6",
VehicleSnap = "2.0.3",
Warehousing = "1.0.3",
["Water-Friendly-Walls"] = "2.0.7",
Waterfill_v17 = "2.0.5",
WideChests = "6.2.4",
["WideChests-aai-reskin"] = "0.2.0",
WideChestsAllTypes = "2.0.0",
WideChestsLogistic = "3.1.1",
Wood_Gasification_updated = "4.2.1",
WoodenBrick = "1.0.11",
Wr_Enhanced_Map_Colors = "1.5.9",
["aai-containers"] = "0.3.2",
["aai-loaders"] = "0.2.7",
["aai-signal-transmission"] = "0.5.3",
["aai-signal-transmission-luarendered-channel-label"] = "2.1.1",
["aai-signals"] = "0.7.1",
["aai-vehicles-miner"] = "0.7.1",
["aai-zones"] = "0.7.2",
["accumulator-walls"] = "2.0.3",
["atan-null"] = "2.0.2",
["automatic-station-painter"] = "2.0.0",
["barrel-stages"] = "2.0.0",
base = "2.0.72",
["belt-visualizer"] = "2.0.2",
bobinserters = "2.0.1",
botReplacer = "2.0.0",
circuit_visualizer = "2.0.2",
["color-coding"] = "2.0.3",
color_whole_train = "2.1.0",
compaktcircuit = "2.0.26",
["concreep-redux"] = "3.3.2",
["construction-train-werl"] = "0.3.3",
cybersyn = "2.0.37",
["cybersyn-combinator"] = "2.7.3",
["deadlock-beltboxes-loaders"] = "2.6.0",
["deep-storage-unit"] = "1.6.8",
depressdog_updater_lib = "0.0.7",
["display-panel-symbols"] = "1.0.0",
electricboiler = "2.0.1",
["elevated-pipes"] = "1.4.5",
["est-tiny-storage-tank"] = "1.4.0",
["even-more-text-plates-2_0"] = "2.0.0",
["even-pickier-dollies"] = "2.7.2",
flib = "0.16.5",
["fluid-connection-indicators"] = "0.2.7",
["fluid-memory-storage"] = "1.7.9",
galore_lib = "1.6.2",
["gas-boiler"] = "0.2.1",
["ghost-painter"] = "1.0.0",
["hazard-stripes"] = "2.0.1",
helmod = "2.2.6",
["icon-badges"] = "1.2.6",
["infinite-radar"] = "2.4.5",
informatron = "0.4.0",
jalm = "2.0.1",
["k2-fluid-storage"] = "1.2.1",
["k2-greenhouse-plus"] = "1.2.0",
["k2-wind-turbine"] = "0.1.2",
kry_stdlib = "2.0.11",
["lane-balancers"] = "1.2.2",
["larger-display-panels"] = "1.0.0",
["loaders-modernized"] = "1.0.4",
["logistic-helper"] = "2.2.0",
["logistic-memory-units-fixed"] = "2.0.0",
lordodin_no_drains = "2.0.2",
["mining-patch-planner"] = "1.7.14",
miningdrones_aaiminer_space_age = "0.0.9",
["nco-LongStorageTanks"] = "2.0.0",
["nco-SmallTank"] = "2.0.0",
["nixie-tubes"] = "2.0.9",
["not-enough-parameters"] = "1.0.1",
["prismatic-belts"] = "2.0.9",
pump = "2.1.18",
pumping_station = "0.2.6",
pushbutton = "2.0.5",
["py-another-early-train"] = "0.1.3",
py_liquidfuel = "0.4.3",
pyalienlife = "3.0.60",
pyalienlifegraphics = "3.0.10",
pyalienlifegraphics2 = "3.0.2",
pyalienlifegraphics3 = "3.0.4",
pyalternativeenergy = "3.1.35",
pyalternativeenergygraphics = "3.0.5",
pycoalprocessing = "3.0.43",
pycoalprocessinggraphics = "3.0.9",
pycranes = "1.1.1",
pyfusionenergy = "3.0.16",
pyfusionenergygraphics = "3.0.4",
pyhightech = "3.0.17",
pyhightechgraphics = "3.0.2",
pyindustry = "3.0.19",
pyindustrygraphics = "3.0.2",
pymodpack = "3.0.0",
pypetroleumhandling = "3.0.21",
pypetroleumhandlinggraphics = "3.0.5",
pypostprocessing = "3.0.39",
pyrawores = "3.0.24",
pyraworesgraphics = "3.0.4",
qol_research = "3.4.2",
resourceMarker = "0.8.33",
["robotworld-continued"] = "2.0.0",
["rusty-locale"] = "1.0.17",
["show-fluid-temperature-in-pipe-and-tank-gui"] = "1.0.4",
["signal-lamp"] = "2.1.0",
smartchest = "2.0.1",
["solar-walls"] = "2.0.3",
["some-autoresearch"] = "2.0.6",
["speaker-signals-expansion-relaunched"] = "2.0.1",
splatter_guard_continued = "21.0.2",
["squeak-through-2"] = "0.1.2",
["stack-combinator-redux"] = "0.4.1",
["switch-button"] = "0.2.3",
textplates = "0.7.2",
["thermal-solar-power-lite"] = "2.1.20",
["tile-aligner"] = "1.0.0",
["tile-upgrade-planner"] = "20.0.1",
tree_collision = "2.0.0",
["turbines-plusplus-reloaded"] = "2.1.12",
["underground-heat-pipe"] = "2.2.2",
["underground-pipe-pack"] = "2.0.6",
valves = "2.1.0",
verysmallchests = "2.0.2",
["virtual-signals2"] = "1.3.0",
["vtk-deep-core-mining"] = "3.2.7",
["water-pumpjack"] = "2.4.2",
["what-is-it-really-used-for"] = "1.7.1",
["wide-aai-chests"] = "0.1.2",
["wide-containers-assets"] = "0.2.10",
["wide-steel-chests"] = "0.2.12",
["zithorian-extra-storage-tanks-port"] = "1.0.6"

Hello

Got the same error, I believe you can reproduce it easily by installing pyblock + fcpu.

I found the error by dichotomy & reproduced with that.

Yes, byplock + fCPU fails to load with the specified string.
However, during debugging I found no evidence that fCPU is the cause.

The Py* mod performs many operations on recipes and fails in one of them.
The error appears to be in pypostprocessing_3.0.39/data-updates.lua:13 and can be fixed with the following change:

local recipe = data.raw.recipe[belt]:standardize()
local _, first = next(recipe.ingredients) -- fix
local belt_count = first.amount          -- fix
local fluid = false

After that fix pY mod failing to load with following more descriptive error: Failed to load mods: Error while loading recipe prototype "logistic-science-pack" (recipe): Value must be a list in property tree at ROOT.recipe.logistic-science-pack.ingredients Modifications: Base mod › Pyanodons Coal Processing › Pyanodons Alien Life › Pyanodons Post Processing

fCPU use logistic-science-pack for it's recipe, it is base technology.
I think that pY modify recipes in some way and fail to start

I able to run pY with fCPU https://pasteboard.co/c7gyzxjPubBe.png, when disabled:
- compaktcircuit (uses logistic-science-pack too)