FUSE: Fix error check in tests, would nil deref on error
FUSE: Fix error check in tests, would nil deref on error

keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client