The mod Transport Drones Fuel revived (0.5.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Transport_Drones_Fuel_revived::on_init()
Transport_Drones_Fuel_revived/control.lua:77: attempt to index local 'search_offset' (a nil value)
stack traceback:
Transport_Drones_Fuel_revived/control.lua:77: in function 'on_init'
core/lualib/event_handler.lua:69: in function <core/lualib/event_handler.lua:64>

took a while but fixed. Had to revamp the code a lot so report any bugs you notice. Fuel depots and requester depots may need to be refilled (the current code is best effort to carry the fuel over).