Hi,
Player from my mod reported a crash related to yours: https://mods.factorio.com/mod/item-cam-2/discussion/680f58ea7d79b0b42bfddbb8
I include a selection-tool to let player pick what (item) to follow, and it gets to deal with on_player_selected_area first. When it does start following, it switches player's controller to ghost, so .cursor_stack turns nil when Tile Upgrade Planner handles the event.
In script/planner.lua local function selected_area, field planner just needs a nil check before also checking valid_for_read to cover for this edge case.
I hope you can find time for this stupid change. For now I've marked your mod as optional dependency so you get to handle the event first.
Thanks
