While it's now possible to exit the focus menu without focusing (and without breaking the game), you still can't focus on anything. The fix in my comment for the last build still works.
Edit: The fix in my comment for the previous build does not, in fact, actually work. It prevents the error from showing up, but you still can't focus on anything.
Using find-and-replace to change
/link><
into
/link>><
seems to help, but it only allowed focusing Submissive for me; I'm not sure why.
I see the problem now: I somehow managed to get myself stuck in a permanent confused state where I have almost all the focuses active at once, despite never manually enabling them, but actually increasing any of the stats soft-locks my game.
Edit 2: This was happening whenever I got the cutscene that unlocks focusing Male and Female after getting to Friends with Benefits with everyone on the island. I went to that cutscene in the code and noticed that it sets $DiscoverState and $Confused State to true at the beginning of the cutscene, and then to true again at the end. I changed it to set both to false at the end, and the cutscene no longer trapped me in the confused state, but focusing is still broken.
In addition to focusing being broken, re-entering the doctor's office replays the cutscene. However, I can confirm that choosing a focus does remove all other focuses; the one that worked for me was Submissive, but it might be the last one the player unlocked.