I suppose this discussion belongs in here, rather than the thread above.
I somehow figured out what the problem was when I was trying to use Dive... it was very random ._.
It was this autotile's fault
Whenever I touched the area in red the game crashed:
I just had to use a normal tileset and now it works fine. I tried the same in v9.0 and it worked too.
And I think I found another glitch. When you tell Brendan to stop following you, he disappears.