The mod Whistle Stop Factories (0.3.4) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event WhistleStopFactories::on_init()
WhistleStopFactories/control.lua:133: attempt to perform arithmetic on local 'ratio_min' (a nil value)
stack traceback:
WhistleStopFactories/control.lua:133: in function 'recipevalidation'
WhistleStopFactories/control.lua:221: in function <WhistleStopFactories/control.lua:200>

I was using the exfret randomizer mod with this, the error happens when trying to create a world