Well, i didn't point out it was obscure for nothing :) i don't think anyone would have encountered that bug in any kind of normal play.
I was actually trying to change a map from being seen as a pvp scenario to being a normal "freeplay" by deleting the lua files related to the pvp gamemode from the save and replacing them with the one lua file that is present in other freeplay maps i had... I hoped it wouldn't mes up the save TOO much, and to my surprise it didn't but also didn't help me achieve what i wanted.
Long story short when i tried to load this franken-map for the first time (with your mod enabled) i got that error. Then i removed TTS from my modlist, loaded the map again, this time it worked, saved the map, then finally enabled TTS again and now it doesn't crash anymore. I'm guessing me resaving the map helped the game generate whatever files he was missing for the map. But i found it curious that only your mod was affected by this broken map, so i figured i'd forward my findings to you. My guess is that this is related to my previous post about your mod not using the new UI style and maybe relying on something from the map itself (which was now missing) during loading.