Damn. I've had a similar looking error originally while testing but then it didn't reoccur when I gave the campaign a proper full playthrough.
I emailed the game devs about it at one point but got no follow-up on it.
I wrote it off as a fluke originally or something that had to do with my system, since I checked everything ten times and couldn't see why this would happen.

Anyway, I'm not even sure if it's a bug with the mod or a bug that exists in the original game, that triggers more commonly in my mod due to some strange circumstance.
The error report is basically so useless that I don't know what to do with it.

For me though, it was always just a CTD. Game would crash and close automatically, I would get back to desktop and see that message, but then there were no further issues with my computer.

I really need to get that fixed but I have no idea what's happening. Guess I'll just have to pester the devs again.

Having looked through the comments on your mod, I am crashing at the same spot as another user. I am crashing when trying to build a fort in Eastern Spain on my way to conquer the two greek cities. Here is a screenshot of where the fort is.

https://steamcommunity.com/sharedfiles/filedetails/?id=2195337577

I'm quite sure it's the same location as the other player, and having not built the camp there I haven't had a crash yet.

Looking very, very closely at the map in the editor I was able to identify an issue where the pathing in that area would mess up if the camp is built (by anyone, player or AI).

For most incorrect pathing the editor has handy things that identify problems for you but this was sadly not one of them and it all looks good until you zoom in to the level where you can almost see insects crawling on the dirt floor.

This issue btw would have been around since version 0.1... 4 years ago. I can't believe how long that's been lurking out there.
I wouldn't in a million years have caught this without you making the screenshot, so I owe you lots of thanks.
(The previous guy said later that the issue seemed to happen regardless so I ignored it, but maybe it's because the AI built the camp afterwards in his game).

Now that I know what the culprit was I'm going to scan around the map to see if a similar issue occurs elsewhere and then I'll release a small patch later this week.