I upgraded from Build 721 (AFAIK) to v0.0.851.

I was outside Harrowdus, visiting for the first time. I went in, investigated the whole town, talked to NPCs, etc, then tried to leave and got kicked out with:

Error

Moonring v0.0.851:

actor_manager.lua:3484: More than one creature exists with ID: 1

Traceback

[love "callbacks.lua"]:228: in function 'handler'
[C]: in function 'error'
actor_manager.lua:3484: in function 'checkCreatureIDs'
state_game.lua:15291: in function 'saveCurrentWorldAndChangeWorld'
state_game.lua:14685: in function 'zoomOut'
state_game.lua:7780: in function 'fixedUpdate'
state_game.lua:2724: in function 'update'
main.lua:1275: in function 'gameUpdate'
main.lua:1295: in function 'update'
[love "callbacks.lua"]:162: in function <[love "callbacks.lua"]:144>
[C]: in function 'xpcall'

I am now stuck there. If I reload the game I'm on the Overworld map and it's just an arrow, no me, and I can't move around. I can only go into the city. If I try to leave the city it kicks me out of the game with the error again.