Need More Info Scene Editor Game will not load map if I edit it, this error appears:

[Lonewarrior]

When I try and make any edit to the main map terrain or navmesh, I get an error message when you get to the training area and try to leave.
I have tested this a few times, reverting to a backup version of my map fixed the issue but any edits to terrain bring this message up again:

 

[MArdA TaleWorlds]

Is this crashing the tools after clicking OK?