I got a really strange error message and my toddler turned into a cat

So, yeah. I've been trying to get my sim pregnant since last night, finally realized she wasn't making memories and decided to retry. I made a new family with a toddler and when I tried to load on I got an error message that literally says "you gave me a crappy GUID" (pictured) and then my toddler turned into a cat. 

Anyone have any fixes? Lol.