class Sass::SyntaxError

because of a faulty template.
It also provides a handy way to rescue only exceptions raised
and the Sass file that was being parsed (if applicable).
such as the line of the Sass template it was raised on
Sass::SyntaxError encapsulates information about the exception,

def add_backtrace_entry(filename) # :nodoc:

:nodoc:
if applicable (defaults to "(sass)").
+filename+ should be the file in which the error occurred,
Adds a properly formatted entry to the exception's backtrace. 
def add_backtrace_entry(filename) # :nodoc:
  @sass_filename ||= filename
  self.backtrace ||= []
  self.backtrace.unshift "#{@sass_filename || '(sass)'}:#{@sass_line}"
end

def initialize(msg, lineno = nil)

+lineno+ should be the line of the Sass template on which the error occurred.
Creates a new SyntaxError. 
def initialize(msg, lineno = nil)
  @message = msg
  @sass_line = lineno
end

def to_s # :nodoc:

:nodoc: 
def to_s # :nodoc:
  @message
end