Why call function rise exception?

[Suliman via Digitalmars-d-learn]

The problem with 31 string.

http://www.everfall.com/paste/id.php?jgsdz7mdbrnm

If I uncomment it, and server response is return 404 code I code 
at runtime throw exception with text:
"Can't parse config: HTTP request returned status code 404"

I thought that checkLinkCode is throw any king exception, and 
tried to wrap it's in try-catch block. But without result. So 
look like it's ok.

I can't understand in which moment and why code is throwing to 
those exception.