They don't even need to turn the dragon into ashes. When her power was introduced, they said that every living thing that enters in the storage space is insta-killed.
She's what, thirteen? If that happened IRL, there wouldn't be mayhem. They'd give her a stern lecture and ground her until she understands that what she did was extremely stupid and dangerous, and that she was a stupid kid.
If she was 16 or more, then she wouldn't be just a stupid child, she...