Please report this error to the mod author.

Error while running event nullius::on_script_trigger_effect (ID 152)
nullius/scripts/drone.lua:67: attempt to index local 'source' (a nil value)
stack traceback:
nullius/scripts/drone.lua:67: in function 'safe_demolition'
nullius/scripts/drone.lua:141: in function 'terraforming_effect'
nullius/scripts/drone.lua:630: in function <nullius/scripts/drone.lua:610>
74775.184 Error ServerMultiplayerManager.cpp:91: MultiplayerManager failed: "The mod Nullius (1.2.14) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event nullius::on_script_trigger_effect (ID 152)
nullius/scripts/drone.lua:67: attempt to index local 'source' (a nil value)
stack traceback:
nullius/scripts/drone.lua:67: in function 'safe_demolition'
nullius/scripts/drone.lua:141: in function 'terraforming_effect'
nullius/scripts/drone.lua:630: in function <nullius/scripts/drone.lua:610>"

I had just launced a couple terraforming drones, and they seemed to work ok, but maybe the last one had a problem?

You're using 1.2.14 from a couple of months ago. This looks like a duplicate of a bug that was fixed in a more recent release.

The problem had to do with deconstructing the launcher that shot a drone before the drone landed, so it's possible to workaround if you need to by not doing that. But you shouldn't need to if you update.

Thanks. Good to know. I tend not to update such significant Mods during a play through so that nothing important changes. Fantastic mod BTW!