Crashes when using Hole and then collapsing remains

[micheus]

I think I have half of a cerebral cell, then I may not be so helpful...
Take a look at this thread from this post

You dump says: Window: autosaver, that means the error had occurred in auto save process...
...and, as the stack trace point to renumber operation I would suggest you to select the whole object and in [B]ody mode use Cleanup from context menu. Maybe, this can eliminate that malformed object - wrong data (sometimes work).

All that thing about Wings3d required closed mesh is true. So, we need to learn how to deal with that. Sorry.