Shut down all instances, logged in with all add-ons and plug-ins that I normally use running. No crash.
I will try shutting down and logging in a few more times over the course of the afternoon, will post if anything happens..
I ran the eval windower.ffxi.get_info() commmand, and no crash/nothing happened.
I ran the eval print(windower.ffxi.get_info().server) command and it returned 0 to the console.
EDIT: I also tried loading and unloading a number of random add-ons (AEcho, Gearswap, etc) and so far no crash either.
UPDATE: Have restarted any number of times now, still no crash. Kudos and thanks to you guys for addressing this and fixing it so fast!