get feed URL and use that to resolve URL if link is empty

[wyy931]

[wyy912]

In the situation I encountered, the RSS subscription address is https://www.fuli51.net/feed, rather than https://www.fuli51.net/. The parsed articleUrl is a number, which when concatenated forms the resolvedURL, such as https://www.fuli51.net/123456. If the baseURL is not used, it would become https://www.fuli51.net/feed/123456, resulting in the article being inaccessible. I am unsure if this is an exceptional case that I have come across.