StaticMatic assigns Haml::Error instances to 'haml_error' when it
rescues exceptions.  The Haml module contains a class called Error,
which is only a few lines long - see lib/haml/error.rb.  This Error
class was simplified after Haml 1.8.2, and now contains only one
public attribute named 'line'.  Haml no longer has (public) error
attributes called 'line_offset' or 'haml_line'.

So the error identification works again if you edit the StaticMatic
file 'base.rb' and change  'haml_error.line_offset' on line 135 to
"haml_error.line", and also change  'haml_error.haml_line'  on line
186 to the same thing.

These line numbers are from StaticMatic 0.9.4.