Fetching comments when the uploader has disabled them

[m040601]

Documenting what happens when trying to fetch comments of a video that has disabled them.

This is a similar behaviour as reported in #212

TLDR: when the video has disabled comments, pipe-viewer ends up displaying a somehow misleading error message.

=>> Search for YouTube videos (:h for help)
> ada zangemann

** GET https://m.youtube.com/results?hl=en&search_query=ada%20zangemann&sp=CAASBggAEAEYAFAe ==> 200 OK (1s)
:: Returning results with a continuation page token...

 1. mxI3FWk7wec Ada & Zangemann - Ein Märchen über Software, Ska Free Soft  3m  1.3K    31:33
 2. ac3ZZ7WUuZM Ada & Zangemann - A Tale of Software, Skateboard Free Soft  5m  1.1K    31:33
 3. ms5vjV4IfoA Ada & Zangemann - Un conte sur les logiciels, le Free Soft  2m   418    31:33
 4. xK2vVRR2iPc Ada & Zangemann - Un cuento sobre Software, Mono Free Soft  2w    38    31:33
 5. 2bHLxFqTnRo Ada & Zangemann: Ein Märchen über Software, Skat Free Soft  3y   607    44:30

Those videos uploaded by the Free Software Foundation Europe have disabled
comments. But lets pretend we dont know that yet, and try to fetch the comments
on the first one,

=>> Select one or more videos to play (:h for help)
> ;c1

We're using the yt-dlp backend first,

:: Extracting comments with `yt-dlp`...
WARNING: [youtube] mxI3FWk7wec: Cannot decrypt nsig without player_url: Some formats may be missing
WARNING: Only images are available for download. use --list-formats to see them
WARNING: [youtube] mxI3FWk7wec: Youtube said: Comments are turned off.
WARNING: Requested format is not available

Actually, yt-dlp got it right, "Youtube said: Comments are turned off". But,
pipe-viewer, ignores that and proceeds to try the alternative invidious
backend,

** GET https://api.invidious.io/instances.json ==> 200 OK
:: Found 0 invidious instances:
:: Found 2 invidious instances: inv.nadeko.net id.420129.xyz
:: Changed the instance to: https://inv.nadeko.net
** GET https://inv.nadeko.net/api/v1/comments/mxI3FWk7wec?hl=en-US&sort_by=top ==> 404 Not Found (1s)
[404 Not Found] Error occurred on URL: https://inv.nadeko.net/api/v1/comments/mxI3FWk7wec?hl=en-US&sort_by=top

[!] No comments results!

=>> Press <ENTER> for the next page of comments (:h for help)

So these last messages are a bit misleading. It's not that there was an "error"
or that there were "no comments". It is simply that the comments are disabled
by the uploader.

[m040601]

Oh, and of course, the last line,

=>> Press <ENTER> for the next page of comments (:h for help)

makes no sense here.