Can't save or export after welding

[micheus]

After welding to remove a hole (...)

If you made use of the .Hole. command to create those holes there is a proper command to remove them - select any face that surround the hole and select the command .Hole. with [RMB] option.

Long stack trace:
[{gb_trees,get_1,[-1,nil],[{file,"gb_trees.erl"},{line,245}]},
{wings_we,'-do_renumber/3-lc$^0/1-0-',2,[{file,"wings_we.erl"},{line,677}]}, (...)

99% of the times we see this log starting with reference to do_renumber is because there is inconsistencies in the mesh - usually caused for "improper" operations. In this case, you probably can fix it by using the command Cleanup in the body [b] mode - after select the object.