Just updated and this appreared.

The mod Bottleneck caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Bottleneck::on_configuration_changed
real number expected got nil.
stack traceback:
Bottleneck/control.lua:83: in function 'new_signal'
Bottleneck/control.lua:110: in function 'built'
Bottleneck/control.lua:142: in function 'rebuild_overlays'
Bottleneck/control.lua:261: in function <Bottleneck/control.lua:244>
stack traceback:
[C]: in function 'newindex'
__Bottleneck/control.lua:83: in function 'new_signal'
Bottleneck/control.lua:110: in function 'built'
Bottleneck/control.lua:142: in function 'rebuild_overlays'
Bottleneck/control.lua:261: in function <Bottleneck/control.lua:244>

I hit this too, but only when loading a map (0.18 of course), which had been using Bottleneck (and it worked, and the new icons are sweet btw!).

Yeah that's a Bug I introduced and fixed, the next release should contain the fix.
Reference: https://github.com/troelsbjerre/Bottleneck/pull/65

Thanks ^^ I really like the mod