Missing train station crashes game

[AndrolGenhald]

If a station is picked up when a train is waiting at it, it will crash the game when the train tries to leave.

To reproduce:

• Make a small track with 2 train stations, A and B
• Have a train go to each station and wait 5 seconds
• When train reaches station B, pick up the station

After 5 seconds game crashes with SIGSEGV

[Bilka]

Duplicate: 57869