[niconico] subtitle-related options result in error

[rivke41levp656]

DO NOT REMOVE OR SKIP THE ISSUE TEMPLATE

• I understand that I will be blocked if I intentionally remove or skip any mandatory* field

Checklist

• I'm reporting that yt-dlp is broken on a supported site
• I've verified that I have updated yt-dlp to nightly or master (update instructions)
• I've checked that all provided URLs are playable in a browser with the same IP and same login details
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched known issues and the bugtracker for similar issues including closed ones. DO NOT post duplicates
• I've read the guidelines for opening an issue
• I've read about sharing account credentials and I'm willing to share it if required

Region

No response

Provide a description that is worded well enough to be understood

yt-dlp errors on niconico URLs if some subtitle related options are provided.
It works as expected with just yt-dlp --ignore-config 'URL' or if given --no-embed-subs
It fails with output identical to the below log if --embed-subs is replaced by --list-subs, as well.

Provide verbose output that clearly demonstrates the problem

• Run your yt-dlp command with -vU flag added (yt-dlp -vU <your command line>)
• If using API, add 'verbose': True to YoutubeDL params instead
• Copy the WHOLE output (starting with [debug] Command-line config) and insert it below

Complete Verbose Output

[debug] Command-line config: ['--ignore-config', '--verbose', '--embed-subs', 'https://www.nicovideo.jp/watch/sm16309076']
[debug] Encodings: locale UTF-8, fs utf-8, pref UTF-8, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version nightly@2023.11.29.232714 from yt-dlp/yt-dlp-nightly-builds [6a9c7a2b5] (zip)
[debug] Python 3.11.6 (CPython x86_64 64bit) - Linux-6.6.2-arch1-1-x86_64-with-glibc2.38 (OpenSSL 3.1.4 24 Oct 2023, glibc 2.38)
[debug] exe versions: ffmpeg 6.1 (setts), ffprobe 6.1, phantomjs broken, rtmpdump 2.4
[debug] Optional libraries: Cryptodome-3.12.0, certifi-2023.11.17, mutagen-1.47.0, requests-2.31.0, sqlite3-3.44.1, urllib3-1.26.18, websockets-10.4
[debug] Proxy map: {}
[debug] Request Handlers: urllib, requests
[debug] Loaded 1792 extractors
[niconico] Extracting URL: https://www.nicovideo.jp/watch/sm16309076
[niconico] sm16309076: Downloading webpage
[niconico] sm16309076: Downloading comments
ERROR: Unable to handle request: Unsupported url scheme: "" (requests, urllib)
Traceback (most recent call last):
  File "/home/user/.local/bin/yt-dlp/yt_dlp/YoutubeDL.py", line 1570, in wrapper
    return func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/YoutubeDL.py", line 1705, in __extract_info
    ie_result = ie.extract(url)
                ^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 717, in extract
    ie_result = self._real_extract(url)
                ^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/niconico.py", line 473, in _real_extract
    'subtitles': self.extract_subtitles(video_id, api_data, session_api_data),
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 3586, in extract_subtitles
    return self._get_subtitles(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/niconico.py", line 481, in _get_subtitles
    legacy_danmaku = self._extract_legacy_comments(video_id, thread_ids, user_id_str, comment_user_key) or []
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/niconico.py", line 545, in _extract_legacy_comments
    return self._download_json(
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 1071, in download_content
    res = getattr(self, download_handle.__name__)(url_or_request, video_id, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 1035, in download_handle
    res = self._download_webpage_handle(
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 905, in _download_webpage_handle
    urlh = self._request_webpage(url_or_request, video_id, note, errnote, fatal, data=data, headers=headers, query=query, expected_status=expected_status)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/extractor/common.py", line 849, in _request_webpage
    return self._downloader.urlopen(self._create_request(url_or_request, data, headers, query))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/YoutubeDL.py", line 4058, in urlopen
    return self._request_director.send(req)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/.local/bin/yt-dlp/yt_dlp/networking/common.py", line 127, in send
    raise NoSupportingHandlers(unsupported_errors, unexpected_errors)
yt_dlp.networking.exceptions.NoSupportingHandlers: Unable to handle request: Unsupported url scheme: "" (requests, urllib)