Neither a teacher nor a native speaker
Would you like some coffee / something to drink? You expect that your guest will accept your offer. Besides, you will offer him/her the best you have at home, of course not any rubbish you have hidden somewhere...., that is to say, anything -pejorative-.
Here, I think it is a "similar" case. Something because there is something there that can hit it. Anything would be - quelque chose n'importe quoi -, I'm afraid I got myself into a mess...- I know it doesn't suit but difficult to explain. I'll keep an eye on future explanations.
I'll keep it in mind and try to find a suitable account.