Is there an app. which looks at a subtitle file, let's say an srt file and tells the user if something is missing. Sometimes .srt file maybe transformed from an *.ass subtitle to *.srt using ffmpeg and am not sure how correct the file is or not. I know that mpv and many others are graceful that they drop those sequences which are perhaps of errors. But neither the viewer or the one who wants to contribute to a better subtitle can do nothing about it.
If there is somehting for that, please let know.