This is a fun way to keep your stations colored, thanks for the mod! Found a small issue:

Error while running event automatic-station-painter::on_train_changed_state (ID 23)
automatic-station-painter/control.lua:59: attempt to index field 'station' (a nil value)
stack traceback:
automatic-station-painter/control.lua:59: in function <automatic-station-painter/control.lua:33>

Using ATP and LTN (though not sure LTN matters). My approximate repro steps are:

1. Train is dispatched to station by LTN.
2. Destination station is renamed while train is en route
3. Crash will occur as the train arrives at the now renamed station

Thanks for the report. I was not able to reproduce it. My attempt was:

1. Open the train's schedule and press > on the next stop;
2. Open the next stop station and change the name;
3. Wait for the train to arrive; and
4. Everything is puppies and rainbows.

This may be a bug in the Factorio API since the event that indicates the train arrived at a station didn't have the station in the train's data structure. Regardless, I've guarded against this case now and hopefully it'll resolve your problem.

maybe a related bug, or something completely different ...

mods used: many, including LTN, Automatic Train Painter, Automatic Station Painter and also Wagon Auto Graphics.
edit: same problem persisted after removing Wagon Auto Graphics

i just installed this mod and updated all mods and all went well until LTN sent some train from a depot. immediately thereafter (i did NOT change any names at this point) the game crashed with the following message. thus i assume it was related to trying to color the depot itself !?

The mod Automatic Station Painter (1.0.1) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event automatic-station-painter::on_train_changed_state (ID 23)
automatic-station-painter/control.lua:81: attempt to index local 'c2' (a nil value)
stack traceback:
automatic-station-painter/control.lua:81: in function 'blend_colors'
automatic-station-painter/control.lua:125: in function 'paint_station'
automatic-station-painter/control.lua:64: in function <automatic-station-painter/control.lua:33>

Thank you for the report. I have identified the problem and will be releasing the fix today.