Repository: youtube-dl
Issue: Failing to parse JSON when downloading from pluralsight
Labels: broken-IE

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## Checklist

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Carefully read and work through this check list in order to prevent the most common mistakes and misuse of youtube-dl:
- First of, make sure you are using the latest version of youtube-dl. Run `youtube-dl --version` and ensure your version is 2021.12.17. If it's not, see https://yt-dl.org/update on how to update. Issues with outdated version will be REJECTED.
- Make sure that all provided video/audio/playlist URLs (if any) are alive and playable in a browser.
- Make sure that all URLs and arguments with special characters are properly quoted or escaped as explained in http://yt-dl.org/escape.
- Search the bugtracker for similar issues: http://yt-dl.org/search-issues. DO NOT post duplicates.
- Finally, put x into all relevant boxes (like this [x])
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- [x] I'm reporting a broken site support
- [x] I've verified that I'm running youtube-dl version **2021.12.17**
- [x] I've checked that all provided URLs are alive and playable in a browser
- [x] I've checked that all URLs and arguments with special characters are properly quoted or escaped
- [x] I've searched the bugtracker for similar issues including closed ones


## Verbose log

<!--
Provide the complete verbose output of youtube-dl that clearly demonstrates the problem.
Add the `-v` flag to your command line you run youtube-dl with (`youtube-dl -v <your command line>`), copy the WHOLE output and insert it below. It should look similar to this:
 [debug] System config: []
 [debug] User config: []
 [debug] Command-line args: [u'-v', u'http://www.youtube.com/watch?v=BaW_jenozKcj']
 [debug] Encodings: locale cp1251, fs mbcs, out cp866, pref cp1251
 [debug] youtube-dl version 2021.12.17
 [debug] Python version 2.7.11 - Windows-2003Server-5.2.3790-SP2
 [debug] exe versions: ffmpeg N-75573-g1d0487f, ffprobe N-75573-g1d0487f, rtmpdump 2.4
 [debug] Proxy map: {}
 <more lines>
-->

```ShellSession
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-i', u'--cookies', u'/pluralsight.com_cookies.txt', u'--sleep-interval', u'60', u'https://app.pluralsight.com/library/courses/configuring-managing-kubernetes-storage-scheduling/table-of-contents', u'-o', u'./kubernetes/helm/configuring-managing-kubernetes-storage-scheduling/%(playlist_index)02d-%(title)s.%(ext)s', u'--verbose']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2021.12.17
[debug] Python version 2.7.16 (CPython) - Linux-5.10.63-v7+-armv7l-with-debian-10.11
[debug] exe versions: ffmpeg 4.1.8-0, ffprobe 4.1.8-0
[debug] Proxy map: {}
[pluralsight:course] configuring-managing-kubernetes-storage-scheduling: Downloading JSON metadata
[pluralsight:course] configuring-managing-kubernetes-storage-scheduling: Downloading JSON metadata
ERROR: configuring-managing-kubernetes-storage-scheduling: Failed to parse JSON  (caused by ValueError('No JSON object could be decoded',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 906, in _parse_json
    return json.loads(json_string)
  File "/usr/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 382, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 815, in wrapper
    return func(self, *args, **kwargs)
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 836, in __extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 534, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/pluralsight.py", line 467, in _real_extract
    course = self._download_course(course_id, url, course_id)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/pluralsight.py", line 93, in _download_course
    headers={'Referer': url})
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 899, in _download_json
    expected_status=expected_status)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 883, in _download_json_handle
    fatal=fatal), urlh
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 910, in _parse_json
    raise ExtractorError(errmsg, cause=ve)
ExtractorError: configuring-managing-kubernetes-storage-scheduling: Failed to parse JSON  (caused by ValueError('No JSON object could be decoded',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
```

## Description

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WRITE DESCRIPTION HERE

I've tried to download some courses and the downloader is unable to parse the JSON. 
I've tried different computers and os's, and also, tried to download a course I downloaded some weeks ago, this time without success.