Fix #4521: If os.path.getsize throws FileNotFoundError, set the retry to resume from 0.

[boredzo]

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Description of your pull request and other information

As of 2023.10.13 and master@4e38e2ae9d7380015349e6aee59c78bb3938befd, when yt-dlp encounters an incomplete read while downloading a WebVTT stream, it may not have created the file for that fragment yet, in which case its attempt to set the resume length on the retry (to the file's length) fails with FileNotFoundError.

This patch catches FileNotFoundError and sets the resume length to 0 in that case.

Fixes #4521.

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Copilot Summary

🤖 Generated by Copilot at 0d37aa9

Summary

🔄🗑️🐛

Handle missing temporary file when resuming download in yt_dlp/downloader/http.py. Set resume length to zero instead of raising an error.

tempfile missing
resume length becomes zero
autumn leaves falling

Walkthrough

• Handle missing temporary file when resuming download (link)

[boredzo]

I got no test failures on PlutoTV or RoosterTeeth, but did see test failures under test_subtitles. However, they also occur on master, so they're not related to my changes.

[pukkandan]

when yt-dlp encounters an incomplete read while downloading a WebVTT stream, it may not have created the file for that fragment yet

This sounds like there is a bigger underlying problem, but I suppose your patch work well enough for now. Could you add a comment to the code?

[memmam]

Hey, what's the status on this being merged in?