appending taxonomy tags to RSS titles

Hi everyone,

I am trying to write a plugin which will modify teh output RSS feed for a blog, such that all the taxonomy tags are appended as hashtags to the post title.

For example, for a post titled “My Great Blog Post” and tagged with “awesome, super amazing, wow”, the RSS feed would show the title of the post as,

“My Great Blog Post #awesome #super_amazing #wow”

The point of this is to make posts very twitter friendly, for those bloggers who pipe their blog posts into their Twitter accounts using twitterfeed or some other similar service.

Unfortunately I am not experienced enough to get this working. I have written the first iteration of the plugin here:

https://pastebin.com/m6ffa2e0e

and the plugin activates fine (ie, no dumb PHP errors at least), but when active the plugin creates an XML error on the output feed.

my suspicion is that I am not using the correct filter hook, or I am not using the filter correctly. As you can see the code is quite simple so I am sure theres some major issue I have missed.

Your assistance would be highly appreciated in resolving this. Thanks!