what do lastException files mean?

im trying to fix my build mode (every time i open it, none of the build/buy menu appears and all i can do is move existing object). apparently the lastException files tell you something about why the game is crashing. i downloaded mc command center back in april, but immediately deleted it because it wasn't showing up. it's very possible that i didn't install or delete it correctly (after i deleted it, i had lost almost all of my previous progress), but out of nowhere in july, i think after some kind of update, my build mode broke. i've heard that the broken build mode is caused by mods, but i thought i didn't have any mods, which is why i'm having so much trouble fixing this. i do, however, have lots of lastException files in my sims 4 folder.

does anyone know what the lastException files mean? i have files that are lastException_(insert long number) and also lastUIException and lastException_(insert long number). are they related to the broken build mode? thank you!!