If a vtt or srt file is not valid in some way we should give a warning during import

[BenjaminScholtens]

Specifically, the chosen has been generating some vtt files using the chatgbt or something like that. And sometimes it messes up the timestamps. So line 3 will have a timestamp that belongs at the end of the file instead of in between a timestamp that belongs in between line 2 and line 4. So that's one thing that we should definitely show an error about or some sort of warning when they are importing a vtt.
We could also show any other parsing errors we can think of or that an LLM can think of, but specifically this non-sequential parsing error has come up a few times now, and we should be giving our users a warning when they're importing.