"I accept there's something strange about you, probably nothing a good beating wouldn't have cured –– and as for all this about your parents, well, they were weirdos, no denying it, and the world's better off without them in my opinion - asked for all they got, getting mixed up with these wizarding types - just what I expected, always knew they'd come to a sticky end ––"
(Harry Potter and the Sorcerer's Stone)
I suppose the construction might be a preterite perfect. In this case, I wonder what the full matrix clause is supposed to be. I guess it could be ‘There would have probably been nothing [a good beating wouldn’t have cured]’. But I’m not sure for I’ve already got one:” "Your strangeness is nothing [pronoun functioning as subject complement] that (relative pronoun) a good beating wouldn't have cured," which makes me confused. What could be the matrix clause?