I made a mod for testing the Modding of Satisfactory. After im ready with all i create a new one (the real one ) and deleted my test mod from the games mod folder. After i loaded my test savegame i got a crash (see image below).
I just made Static Meshes. Nothing special.
I hope this is helpfull because the docs says that every object from a mod which is not there anymore will be automatically removed from the savegame/world.