The mod Auto Ghost Builder (0.1.5) caused a non-recoverable error.
Please report this error to the mod author.

When auto placing underwater pipes from the Undewater Pipes mod by hovering the mouse over the pipe.

Error while running event AutoGhostBuilder::on_selected_entity_changed (ID 56)
The mod Underwater Pipes (Kux' re-publication) (3.0.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Kux-UnderwaterPipes::script_raised_revive (ID 88)
Kux-UnderwaterPipes/control.lua:54: attempt to index local 'player' (a nil value)
stack traceback:
Kux-UnderwaterPipes/control.lua:54: in function <Kux-UnderwaterPipes/control.lua:24>
(...tail calls...)
Kux-UnderwaterPipes/control.lua:151: in function <Kux-UnderwaterPipes/control.lua:147>
stack traceback:
[C]: in function 'revive'
AutoGhostBuilder/control.lua:83: in function <AutoGhostBuilder/control.lua:37>

It seems like the mod UnderwaterPipes was to blame. It was broken.