The mod Transport Drones (1.0.18) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Transport_Drones_Meglinge_Fork::on_lua_shortcut (ID 38)
Value must be a string in property tree at ROOT.tooltip
stack traceback:
[C]: in function 'add'
Transport_Drones_Meglinge_Fork/script/gui.lua:217: in function 'update_contents'
Transport_Drones_Meglinge_Fork/script/gui.lua:281: in function 'update_supply_depot_gui'
Transport_Drones_Meglinge_Fork/script/gui.lua:302: in function 'update_supply_tab'
Transport_Drones_Meglinge_Fork/script/gui.lua:373: in function 'add_fluid_tab'
Transport_Drones_Meglinge_Fork/script/gui.lua:675: in function 'make_network_gui'
Transport_Drones_Meglinge_Fork/script/gui.lua:702: in function 'refresh_network_gui'
Transport_Drones_Meglinge_Fork/script/gui.lua:789: in function 'open_gui'
Transport_Drones_Meglinge_Fork/script/gui.lua:919: in function 'toggle_gui'
Transport_Drones_Meglinge_Fork/script/gui.lua:925: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

This happened after I pressed the Toggle Road Network GUI button.