Errors in Sass aren't reported gracefully

In messing about with this: http://github.com/charlesr/staticmatic-compass-susy

I started getting an error reported by staticmatic (see below). The wording of the error gives the impression that there's an error with Haml, but it turns out to be an error in my Sass. It doesn't matter what the problem with the Sass is - it always gives the same error. This could do with tidying up a bit.

@@@[ D:\Code\Projects\Staticmatic_Compass_Susy ]

staticmatic preview . Site root is: D:/Code/Projects/Staticmatic_Compass_Susy
StaticMatic Preview Server Starting...
Running Preview of D:/Code/Projects/Staticmatic_Compass_Susy on :3000
Thu Oct 29 18:42:25 +0000 2009: Read error: #<NoMethodError: private method gsub' called for nil:NilClass><br/> (haml):17:inrender' C:/ruby/lib/ruby/gems/1.8/gems/haml-2.2.9/lib/haml/engine.rb:168:in render'<br/> C:/ruby/lib/ruby/gems/1.8/gems/haml-2.2.9/lib/haml/engine.rb:168:ininstance_eval'
C:/ruby/lib/ruby/gems/1.8/gems/haml-2.2.9/lib/haml/engine.rb:168:in render'<br/> C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/mixins/render.rb:98:ingenerate_html_from_template_source'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/mixins/rescue.rb:10:in render_rescue_from_error'<br/> C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/mixins/render.rb:83:ingenerate_css'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/server.rb:32:in process'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/http_response.rb:65:instart'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/server.rb:24:in process'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:159:inprocess_client'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:158:in each'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:158:inprocess_client'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:285:in run'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:285:ininitialize'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:285:in new'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:285:inrun'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:268:in initialize'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:268:innew'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel.rb:268:in run'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/configurator.rb:282:inrun'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/configurator.rb:281:in each'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/configurator.rb:281:inrun'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/server.rb:88:in cloaker_'<br/> C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/configurator.rb:50:incall'
C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mingw32/lib/mongrel/configurator.rb:50:in initialize'<br/> C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/server.rb:82:innew'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/server.rb:82:in start'<br/> C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/mixins/server.rb:4:inpreview'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/base.rb:60:in send'<br/> C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/../lib/staticmatic/base.rb:60:inrun'
C:/ruby/lib/ruby/gems/1.8/gems/staticmatic-0.10.6/bin/staticmatic:23
C:/Ruby/bin/staticmatic:19:in load'<br/> C:/Ruby/bin/staticmatic:19@@@