I encountered this error:

656.047 Info AppManagerStates.cpp:1844: Saving finished
716.287 Info AppManagerStates.cpp:1844: Saving finished
751.723 Info AppManagerStates.cpp:1844: Saving finished
792.289 Error MainLoop.cpp:1202: Exception at tick 35439269: The mod Transport Drones (0.5.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Transport_Drones::on_robot_built_tile (ID 47)
Transport_Drones/script/road_network.lua:457: attempt to index local 'network' (a nil value)
stack traceback:
Transport_Drones/script/road_network.lua:457: in function 'remove_depot'
Transport_Drones/script/depots/request_depot.lua:444: in function 'remove_from_network'
Transport_Drones/script/road_network.lua:258: in function 'set_node_ids'
Transport_Drones/script/road_network.lua:329: in function 'add_node'
Transport_Drones/script/proxy_tile.lua:35: in function 'road_tile_built'
Transport_Drones/script/proxy_tile.lua:117: in function 'handler'
core/lualib/event_handler.lua:44: in function <core/lualib/event_handler.lua:42>

Running version 0.5.2
Here's the save game including the mod not on the portal.
https://1drv.ms/u/s!AlduFs-osXHvjC7Abn2ESXqkJUhv?e=sMQgxD
Don't move and let it run for about 40 seconds

Thank you so much for the great report, and including the save game

I was able to use it to debug and find the root issue, and it is now fixed for the next release

It works. Thank you for the quick fix. I'm glad you could find the root issue.