Info if Jasper cares to look further into it...
If Jasper followed through and went to go investigate Ella's ladderless treehouse, he would've found it in disarray from the storm and it appeared that she was living in the (formely) abandoned hut next to it instead. There are several empty and half-full liquor bottles scattered around, along with numerous copies of different versions of the Peter Pan books stacked next to her makeshift bed of piled blankets. There are no other personal items, despite her permanently living there, which may indicate that she took them with her. She was seen wearing a backpack before she entered the rift, suggesting that her disappearance may have been deliberate.
From Chapter 15 of Peter and Wendy:
"Pan, who and what art thou?" he cried huskily. "I'm youth, I'm joy," Peter answered at a venture, "I'm a little bird that has broken out of the egg."