Sometimes, removing a connector causes the following error:

Error while running event pipelayer::on_tick (ID 0)
LuaFluidBox API call when LuaFluidBox was invalid.
stack traceback:
pipelayer/Connector.lua:67: in function 'ready_as_output'
pipelayer/ConnectorSet.lua:121: in function 'next_output'
pipelayer/Network.lua:378: in function 'try_to_transfer'
pipelayer/Network.lua:396: in function 'update'
pipelayer/Network.lua:364: in function 'task'
pipelayer/lualib/Scheduler.lua:11: in function 'on_tick'
pipelayer/Network.lua:478: in function 'update_all'
pipelayer/Editor.lua:488: in function 'on_tick'
pipelayer/control.lua:50: in function <pipelayer/control.lua:50

Unfortunately, I can't pin-point the cause. The error happens only with a handful of specific connectors, but for those it is reproducible (i.e. the affected connectors can no longer be removed without causing the error in question).

I don't think any of the other mods in use are connected to the crash, but here is a list of what I am using:
Bottleneck
DeadlockLoaders + DeadlockStacking
LTN + LTN_Content_Reader
InventorySensor
PickerExtended
TrainOverhaul
VehicleGrid
RailTools
WideChests
RSO + Angel infinite ores
auto-research
beltlayer + pipelayer
far-reach

Let me know in case you need any additional information.