In Chapter 28 of To Kill a Mockingbird why did Aunt Alexandra bring Scout her overalls, rather than a dress?

From the text:

“Aunty, is Jem dead?”

“No—no, darling, he’s unconscious. We won’t know how badly he’s hurt until Dr. Reynolds gets here. Jean Louise, what happened?”

“I don’t know.”

She left it at that. She brought me something to put on, and had I thought about it
then, I would have never let her forget it: in her distraction, Aunty brought me my
overalls. “Put these on, darling,” she said, handing me the garments she most despised.

Aunt Alexandra is so distracted by Jem's injuries that she grabbed Scout's overalls by mistake. At this point, it doesn't really matter.