I think the spoiler is because of where the sign is... I'll put the next part spoiler just in case....(it's what fans think of where the place is)
Althought it seems quite obvious, the sign seems to hovering above Hogwarts... that would mean someone from Hogwarts was killed. If this was true, then it seems that it's not Ron, Hermione, or Ginny.... because they all looking at the sign....of course, I could always be wrong, you never know with Jo