Insert the following line at the beginning of function create_gui(player, entity) [control.lua, line 1357 in v.0.18.11]
if not global.combinators983[entity.unit_number] then return end -- (KUDr) do nothing if it is an unknown combinator from previous mod incarnation
This happens because the mod doesn't share global (savegame) data with the original mod, so the combinator has no record here.
