EDIT 25.04.19: The issue has been fixed in latest revision.
EDIT 22.04.19: Hotfix 0.62d has been issued, i'll be monitoring crashes to check if the following issue has been solved. There is now new tutorial in game, happy crashing it.
Hello folks, the case of following crash...
ArgumentOutOfRangeException: Argument is out of range. (...) CAT_XriumController.CAT_PlantCombineMultimaterialMeshes (...)
...is still being investigated, and will get hotfixed as soon as i can localize the issue. Unfortunately, even with patient help of our testers, the crash happens very inconsistently and randomly (On same save it can happen in very first minutes, or doesn't crash for hours), but before update 0.63 the issue should hopefully get fixed.
Meanwhile, please save often, as no other workaround is known. Sorry for the inconvenience.