Error while running event Transport_Drones_Meglinge_Fork::on_entity_died (ID 4)
LuaForce doesn't contain key kill_count_statistics.
stack traceback:
[C]: in function 'index'
...nsport_Drones_Meglinge_Fork/script/transport_drone.lua:743: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

Replace the problematic lines with this:
entity.force.get_kill_count_statistics(entity.surface).on_flow("transport-drone-1", 1)
event.force.get_kill_count_statistics(entity.surface).on_flow("transport-drone-1", -1)

@Hromon, even with your suggested patch I get the same error

Error while running event Transport_Drones_Meglinge_Fork::on_entity_died (ID 4)
LuaForce doesn't contain key kill_count_statistics.
stack traceback:
[C]: in function 'index'
...nsport_Drones_Meglinge_Fork/script/transport_drone.lua:743: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

Can you give me your archive? I will fix this issue.