So I managed to lure Erie into her room...
Basically I just ran around counterclockwise when I entered the library, looking for doors, and fled into her room before she caught...me. As it turns out, unlike in Christmas Curse, the stripy background doesn't pull itself up in parallel. Erie just phases her head through the wall. We should get the stripes to pull the top of the door up again or just make a taller door. Also, as it turns out, she didn't care. She just did the usual aaaaaaaand complained to Angell in first-person about things not going her way as the manager of the library when in reality nothing will go her way until she halts her job either by getting distracted or by leaving the library for a bit. Anyway. There is a screenshot of her about to phase through the upper wall with no choice but to exit the dead-end. Programming-wise.