Improved handling of playlists with broken files

[agios]

When MA is reading local playlists and it encounters a file which is missing, or in a format that it cannot handle, the rest of the playlist is skipped entirely.

It would be nice if it continued trying the rest of the list, as otherwise any mistake results in a truncated playlist.

[agios]

The more I think of it this should be considered a bug, will open it in the issue tracker