The mod Quality upgrade planner (2.5.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event quality-upgrade-planner::on_player_selected_area (ID 53)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__quality-upgrade-planner/scripts/modes.lua:52: in function '?'
quality-upgrade-planner/control.lua:165: in function <quality-upgrade-planner/control.lua:156>

If it matters, the error occurred while on the special surface from Blueprint Sandboxes

thanks, this should be fixed now in 2.6.1, some of my code runs after a machine gets marked for upgrade but if another mod (like blueprint sandboxes) causes them to upgrade instantly it would invalidate some references.