Hey, I was inclined to say that because the map doesn't contain any scripts, it was a separate mod on your end. However, when I went ahead and tested it, I also seemed to get errors.

Seems like the duplicator is getting ♥♥♥♥♥♥, although there does seem to be other saves that people have loaded up. Strange!

[ERROR] lua/includes/modules/duplicator.lua:370: bad argument #1 to 'pairs' (table expected, got nil)
1. pairs - [C]:-1
2. CopyEntTable - lua/includes/modules/duplicator.lua:370
3. Copy - lua/includes/modules/duplicator.lua:510
4. CopyEnts - lua/includes/modules/duplicator.lua:541
5. SaveMap - lua/includes/gmsave.lua:82
6. unknown - gamemodes/sandbox/gamemode/save_load.lua:27
7. unknown - lua/includes/modules/concommand.lua:69

Presumably it might be a certain entity on the map, although honestly there aren't many. I'll check through the VMF and see if anything catches my eye!