Check for empty playlists after filtering, and after downloading videos

[benoit74]

Fix #375

Two problems have been fixed:

• scraper was checking the playlist is not empty before filtering by date range, deleted videos, ... => some playlists finally empty were not detected
• scraper was not checking wether the playlist is empty after downloading videos (we could have a majority of videos OK, but all videos of a playlist fails then the playlist is empty

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.

Project coverage is 1.25%. Comparing base (bc1de9e) to head (8e351ba).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
scraper/src/youtube2zim/scraper.py	0.00%	11 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main    #376      +/-   ##
========================================
- Coverage   1.25%   1.25%   -0.01%     
========================================
  Files         11      11              
  Lines       1114    1120       +6     
  Branches     163     165       +2     
========================================
  Hits          14      14              
- Misses      1100    1106       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[rgaudin]

👍