Hmm. The error is that I've used a function, delete-duplicates, that's apparently not part of your Emacs environment. Sorry about that, I was under the impression that it was a standard function.
I'll look into removing that function call or finding out where the delete-duplicates function can be found.
Okay, found it. delete-duplicates is from a
CommonList extension to Emacs. If you're lucky it's already installed, just not automatically loaded. Try adding the line "(require 'cl)" to your .emacs file, before the two require statements for dommod-mode and dommap-mode.
If that doesn't sort it, you'll have to find and download this package (it's hopefully a standard package for your distribution); and if that doesn't work, let me know and I'll try to rewrite the code to do away with those function calls. That might take some time before I get the opportunity to do, though.