Vim: silence some fold-related errors
Vim: silence some fold-related errors

I've been seeing a bit of "E490: No fold found" in an intermittent
sense. Let's see if a bit of the `silent!` treatment helps out.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent