How do I find out which file(s) an app is trying to read at launch?
Try using opensnoop:

sudo opensnoop


(You can also use -n to specify the process name, but it doesn't work with arguments that contain spaces by default. To fix it, replace "'$pname'" with "'"$pname"'" in /usr/bin/opensnoop.)

You could also try to delete files in ~/Library/Containers/ or ~/Library/Saved Application State/.