V1.997 delete tvshow directory, scraping for others stops

To reproduce it:

- With some tvshow directories, with their tvshow.nfo etc as usual
- Delete or rename one of the directories, so XBMC-C doesn't "see" it
- Start tvshow scraping

In v1.988 some weird errors happen, and scraping stops when reaching the unavailable dir. If you enter in configuration, XBMC-C detects that there is no tvshow.nfo, but not that the dir doesn't exist, so if you allow it to try to save a new tvshow.nfo, some new weird errors...

In v1.997 there are no errors shown but the tvshow dirs after the absent one are not scraped, and nowhere in the logs (normal nor debug) is shown that the directory could not be accessed. Behaviour in configuration is the same as in v1.988.