This happens to a station that exists before 1.2 which has network ID A . Clicking it and then directly change to each causes the game to crash:

The mod Project Cybersyn (1.2.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event cybersyn::on_nth_tick(2)
__cybersyn__/scripts/central-planning.lua:340: attempt to index field 'network_flag' (a number value)
stack traceback:
    __cybersyn__/scripts/central-planning.lua:340: in function 'tick_dispatch'
    __cybersyn__/scripts/central-planning.lua:713: in function 'tick'
    __cybersyn__/scripts/main.lua:835: in function <__cybersyn__/scripts/main.lua:834>

If I empty the signal (right click) then change to each it doesn't crash.

Found the issue, it will be fixed in the next update.

In the meantime you can avoid crashing if you change the station to fuel loader mode, change it to each, and then back to station mode.
Disabling all circuit network inputs to the combinator should also work.