Fun game, great job with coming up with a unique concept and making it a reality in such a short time!
I also encountered a bug with the web version (Chrome on Windows 10) and fullscreen mode.
When trying to close my inventory using ESC, the fullscreen mode also disabled. This somehow caused my character to teleport below the bounds of the hub area. I suspect it has to do with player positions relative to screen coordinates.
I managed to escape by walking to the right into the dungeon.