The mod Warptorio2 Expansion (0.18.60) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event warptorio2_expansion::on_research_finished (ID 18)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
	__warptorio2_expansion__/control.lua:2683: in function <__warptorio2_expansion__/control.lua:2680>
stack traceback:
	[C]: in function '__index'
	__warptorio2_expansion__/control.lua:2683: in function <__warptorio2_expansion__/control.lua:2680>