Got it, thanks. Wow, your prefs.json was 176MB!? WTH... it's almost entirely a repeated sequence of bytes:
Looks like maybe a bad UTF8 encoding of a path or something, but I have no idea why that would happen. Maybe your path has Unicode characters in it? Can you say what the actual full path was? It is something like this:
I've changed how preferences are saved in 1.6.32 (now up) so hopefully this doesn't happen again. Unfortunately this means that your preferences will get reset more often if I add or remove something stored in the preferences, but that doesn't happen very much.