I'm getting the following whenever rotating pipes from the Advanced Fluid Handling mod
(https://mods.factorio.com/mod/underground-pipe-pack)

It's not causing a crash, just popping up error messages all the time.

Error while running event fire_department::script_raised_built (ID 77)
fire_department/control.lua:455: attempt to index field 'entity' (a nil value)
stack traceback:
fire_department/control.lua:455: in function <fire_department/control.lua:454>
stack traceback:
underground-pipe-pack/scripts/rotate-and-toggle.lua:119: in function <underground-pipe-pack/scripts/rotate-and-toggle.lua:92>
[C]: in function 'pcall'
underground-pipe-pack/lib/event.lua:271: in function 'dispatch_event'
underground-pipe-pack/lib/event.lua:342: in function <underground-pipe-pack/lib/event.lua:305>

I should add, not sure if I should post on the other mod's page or not. It says this mod had the error, but perhaps I need to post it on the other mod's page? let me know.

Fixed :)