[extractor/youtube:comments] Deep check response for incomplete data

[coletdjnz]

YouTube may sometimes return no comments for a continuation

Authored by: coletdjnz

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

Sometimes YouTube may return no comments for a continuation. This introduces a more throughout deep check for incomplete data to handle this case better.

Example: https://www.youtube.com/watch?v=d_n1qT9uEdU (newest and top sort)

TODO: more thorough testing

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

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• Fix or improvement to an extractor (Make sure to add/update tests)
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• Core bug fix/improvement
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Copilot Summary

🤖 Generated by Copilot at 4f8c1e2

Summary

🛠️🔎🗣️

Improve YouTube comment extraction in yt_dlp/extractor/youtube.py by refactoring and enhancing the logic for finding and processing comment data.

Sing, O Muse, of the skillful coder who refined
The extraction of comments from YouTube's vast domain,
Defining a common path, a clear and constant guide,
To traverse the nested data with ease and without strain.

Walkthrough

• Define a common path to access continuation items in YouTube responses (yt_dlp/extractor/youtube.py, link)
• Pass a list of nested keys to check for comment data in responses, depending on the continuation type (yt_dlp/extractor/youtube.py, link)
• Simplify the loop over continuation items by using the defined path and removing unused assignment (yt_dlp/extractor/youtube.py, link)

[coletdjnz]

Noticing it may throw some some more incomplete data errors where before youtube gave a continuation with no comments, then the following was the end (with no more comments)

[coletdjnz]

issue: videos with no comments are throwing incomplete data errors fixed