No error handling in {html-include} macro if content is unavailable, not found or has the wrong content-type

I want to use this to display a list of internal build/test environments. Sometimes these are on an old old build, and sometimes they're shut down while a build is being loaded.

If I use html-include, I get "Error rendering macro: null" when the webserver is down, and when the referenced page doesn't exist, I get the contents of the webserver's 404 error.

What I'd like to be able to do is display "notfound" and "unavailable" arguments to the macro, e.g.

{html-include:url=http://todd-viegut:7001/profinia/AppInfo|notfound=old build|unavailable=site down}