ashleighinit First, I highly recommend making sure that OneDrive has no access to Sims files. See https://forums.ea.com/discussions/the-sims-4-technical-issues-pc-en/current-issue-sims-4-savesuser-content-disappearing-pc/11838402
Second, there's nothing there that indicates whether or not a mod caused the problem - only a low chance that it might be related to a particular bit of code. Please rename the Mods folder, delete the file called localthumbcache, and do again what you were doing to see if the game itself generates a lastexception file. Let me know what the game was doing when that happened.