I just found this when I was re-reading Harry Potter and the Half-Blood Prince.
It says: “I had it all tested for poison,” he assured Harry, pouring most of the first bottle into one of Hagrid’s bucket-size mugs and handing it to Hagrid. “Had a house-elf taste every bottle after what happened to your poor friend Rupert.”
If you’re doubting me, got to Chapter 22: After The Burial. The error is that it says Rupert, as in Rupert Grint, the actor who played Ron Weasley, instead of Ron. 😀