RunActivity.exe generates a NullReferenceException at startup with debugger attached

[Ryan Young]

1) Launch RunActivity.exe with the Introductory Train Ride activity on the Hisatsu Line ("-start -activity C:\Path\To\MSTS\ROUTES\JAPAN2\ACTIVITIES\itr_e1_s1_w1_t1.act") with the Visual Studio debugger attached.

2) Just before the loading sequence completes, the Orts.Viewer3D.Debugging.DispatchViewer.InitData() function throws a NullReferenceException (at line 296 at the time of writing) and halts the simulator.

3) Without a debugger, this exception would get eaten by a try {} catch {} block. With one attached, it is still possible to continue past it, but it's quite irritating to have this happen at the beginning of every debugging session.