Before this change if a directory entry could be listed but not
lstat-ed then rclone would give an error and abort the directory
listing with the error
failed to read directory entry: failed to read directory "XXX": lstat XXX
This change makes sure that the directory listing carries on even
after this kind of error.
The sync will be failed but it will carry on.
This problem was caused by a programming error setting the err
variable in an outer scope when it should have been using a local err
variable.
See: https://forum.rclone.org/t/sync-aborts-if-even-one-single-unreadable-folder-is-encountered/39653