[bug] error extracting status content: no content found

[tsmethurst]

This occurs sometimes on posts that are just an image and no text:

time=2022-05-13T22:16:51+02:00 level=info msg=ASStatusToStatus: error extracting status content: no content found statusURI=https://mastodon.social/users/yogthos/statuses/108296425480940485

I thought I'd fixed this but apparently not quite!

[NyaaaWhatsUpDoc]

I just realised if you look at the log entry, it's at info level so it's part of that code block that logs the error but doesn't actually stop parsing because of it. I think we might want to update those log messages to be warnings and not look like errors :')

[tsmethurst]

I think in this case we can even just have the ExtractContent function return an empty string and no error if nothing is found; even warnings aren't really necessary if there's just nothing in the status to show I reckon. I'll make a PR for it