Is saying a child who has not reached puberty but died before reaching it is in Jannah?

Assalamualaikum, I actually know that a person's sins are started counting when he reaches puberty, but if someone dies before reaching puberty, is he/she in Jannah? And will I be held sinful for saying a child not reached puberty but died before reaching it in Jannah? In my case, I was thinking about daughter of Kobe Bryant who died in helicopter crash and I thought if she died before puberty, she is in Jannah but after I checked her age, she was way past puberty so I said in my mind she could not be in Jannah, although I didn't speak any of it or act on it, **will I still be sinful?**