BUG: Station validity is not checked before access

[OvermindDL1]

As per https://mods.factorio.com/mods/simwir/ShuttleTrain/discussion/694 the Shuttle-Train mod breaks when the Dynamic Stops mod is used. Although Dynamic Stops seems to be causing it, the failure is in this mod as this mod is not checking for validity of the stations before accessing them. As per my response on that thread:

Since the other mod quick adds and replaces the stops that might be the reason, but this might fix it (untested):
On line 93 change: if string.find
To become this: if station.valid and string.find

It might break again on line 98 (the table.sort) though, if it does could just delete it for now (will not show things sorted then), or maybe try changing it to be this:

table.sort(global.filtered_stations[player_id], function (a, b)
  if not a.valid or not b.valid then return false end
  return a.backer_name < b.backer_name
end)