API: thumbnails not found in Api response

[rkratky]

branch: iss143-test-audio-quality

I don't think I saw this before:

Strangely, it happened with a query that worked just seconds before.

[rkratky]

After the first occurrence of this error, the same query never worked again (the number of results was displayed -- just not the actual results). Restarting the program fixed it, and I can't reproduce it anymore :/

[nick42d]

I have been able to reproduce this with youtui get-album MPREb_HzRLg8XTLkv. Let me take a look. Looks like a good case for #129 too, I should log failed 'test.json's for all queries (in a temp directory).

[nick42d]

Various Artists doesn't have a thumbnail, so seems that this should be an optional field.

[nick42d]

Would also impact playlists; youtui get-playlist VLRDCLAK5uy_lMzHW51iFg1Kx0d_2EHpzbOgCrwtu8cgI