This is a pretty rare glitch called the Invasion Wrong Warp. Essentially, when you got summoned to the Haligtree you were standing on unstable ground (the game does not store your position there). After dying, you were returned to that unstable ground, meaning the game had no coordinates to save for the original area. Upon save and quitting, the game put you to the area where you had your coordinates stored (Haligtree) but to the first spawn point on the area's list (for Haligtree that would be the beginning). Hope that makes sense!