Changing class lineless convoys - crash

[Ves]

Using the savegame we have used recently to debug stuff, open any convoy window and open its individual schedule. Change the schedule by deleting a stop so it gets its individual schedule and then close it again.
Now open the class manager and try to reassign the classes and it should crash.

[jamespetts]

Thank you for that report - I think that I have now fixed this issue. I should be grateful if you could confirm.