error on accessing scheme when it's missing

I got "no such method 'lc'" when fetching a site with LWP::Simple. I think it'd be nice to have a proper error message.

Before:

    $ perl6 -MURI -e "URI.new(q{vg.no}).default_port"
    No such method 'lc' for invocant of type 'Any'
      in method scheme at lib/URI.pm:138
      in method default_port at lib/URI.pm:150
      in block  at -e:1

After:

    $ perl6 -MURI -e "URI.new(q{vg.no}).default_port"
    URI is missing a scheme
      in method scheme at /home/dagurval/dev/uri/lib/URI.pm:138
      in method default_port at /home/dagurval/dev/uri/lib/URI.pm:152
      in block  at -e:1