Got the below error code while laying steam pipes about 2 hours into a new run. I don't have a save file of the exact point of the run it happened but I could get you fairly close.

Error while running event exotic-industries::on_tick (ID 0) invalid key to 'next'
stack traceback:
[C]: in function 'next'
exotic-industries/scripts/control/powered_beacon.lua:75: in function 'update_fluid_storages'
exotic-industries/control.lua:231: in function 'updater'
exotic-industries/control.lua:87 in function
<exotic-industries/control.lua:86>