In Deathly Hallows, Hermione had packed everything – clothes, money and books – but not food.
They were practically starving when they were on the run. Earlier she’d played an extension charm on her bag, so why didn’t she include some canned food? All they had to eat was what they could scavenge, like fish, mushrooms and a few things bought from a shop.
Hermione thinks of everything, so why didn’t she pack food? She had enough time: she could have bought it when getting money from the bank, or when she bought the food from the shop on the run, or even when they were in Grimmauld Place. So why did she forget this?