So i did a bunch of searching and I couldnt find a solution despite this being brought up a few times. I spent 5 hours making a custom map, and when I went back in to finish, the map crashed, nothing would load, and i got a bunch of error messages prohibiting me from going in and finishing the work i spent on this map.

The biggest bugs are terrain heights not loading, a "Object Reference not set to an instance of an object" error, and when I disabled most mods except loading screen mod, airport roads, fine road anarchy 2, and forest brush, an error comes up saying "Simulation Failed: EndDeserialize (Vehicle Manager) tag mismatch"

What is going on here? I see people use mods and assets to make cool maps all the time and when I go in to make one, I cant do it right apparently. How do i load my map up again?