So, if you have any coal powered stone or steel furnaces in your inventory or even a box, the game crashes if you have Factory Levels by sensenmann active.
EDIT: I was wrong about things being fine if you didn't have coal furnaces in your inventory. It crashes as soon as the electric furnace finishes the first plate.
First error message occurs with coal furnaces in inventory. Second message occurs with all coal furnaces placed down.

Error while running event factory-levels::on_built_entity (ID 6)
Unknown entity name: electric-stone-furnace-level-8
stack traceback:
[C]: in function 'create_entity'
factory-levels/control.lua:379: in function 'upgrade_factory'
factory-levels/control.lua:510: in function 'replace_built_entity'
factory-levels/control.lua:529: in function <factory-levels/control.lua:520>

[C]: in function 'create_entity'
factory-levels/control.lua:379: in function 'upgrade_factory'
factory-levels/control.lua:422: in function 'replace_machines'
factory-levels/control.lua:471: in function <factory-levels/control.lua:451>