I receive the following error when placing a Dark Matter replicator with the Utilization Monitor mod enabled:

35.884 Error MainLoop.cpp:864: Exception at tick 6559201: Error while running event UtilizationMonitor::on_tick (ID 0)
Index out of inventory bounds.
stack traceback:
UtilizationMonitor/control.lua:59: in function 'is_working'
UtilizationMonitor/control.lua:72: in function 'update_entity'
UtilizationMonitor/control.lua:135: in function <UtilizationMonitor/control.lua:124>

I'm submitting this here because the monitor worked fine until I placed my first replicator - I assume it's something that most other mods do that it's expecting, combined with bad error handling. :)

I'll also submit this on the Utilization Monitor thread - seems like some defensive programming could have helped here, and maybe y'all could collaborate to figure out what's going on.

Thanks!

Your error message shows that the Utilization Monitor crashes on line 59 of control.lua. I downloaded the Utilization Monitor mod and glanced over its code and it seems to be that the problem is that Utilization Monitor assumes that every lab has exactly seven input slots. Because the replication lab has four slots, there is a crash when you place such a lab down and Utilization Monitor tries to access the nonexistent slot #5.

I can't fix this bug my changing my mod. However, if you open up Utilization Monitor's control.lua file then you can replace lines 58 and 59

for i = 1, 7 do
  local item = inventory[i]

with the line

for i,item in ipairs(inventory) do

which should in theory allow Utilization Monitor to work with labs of any inventory size.

I mean, I guess I could change it on my end by adding three more item slots to the replication lab. But the items in those slots wouldn't ever be used for research and their presence might confuse some players, so I won't.

Ah-hah. Okay, makes sense then. Mind if I quote you over on the bug report I made on the Utilization Monitor mod?

Go right ahead.

It looks like your patch breaks lab utilization, but at least it isn't crashing my game now. I think anything else is on UM's end though.

Thanks for the help!