Syntax error brings site down.

The following incorrect syntax (spot the missing { ):

.addthis_toolbox 
  float: left;
  a {
    float: left;
  }
}

...crashed my server completely (Server not found error), the following was in the error logs:

Apr  3 14:42:22 d7-102-jhadley drupal: http://devel.ssgb.drupal.uk.sift.com|1333460493|php|172.17.201.102|http://devel.ssgb.drupal.uk.sift.com/favicon.ico||0||Notice: Uninitialized string offset: 40105 in SassParser->scss2Token() (line 676 of /data/drupal7/sites/ssgb/site/sites/all/themes/sasson/phamlp/sass/SassParser.php).
Apr  3 14:42:22 d7-102-jhadley drupal: http://devel.ssgb.drupal.uk.sift.com|1333460493|sasson|172.17.201.102|http://devel.ssgb.drupal.uk.sift.com/favicon.ico||0||SassContextException: Undefined Variable: body_text: sites/all/themes/ssgb_sasson/styles/ssgb_sasson.scss::44#012Source: color: $body-text in SassContext->getVariable() (line 88 of /data/drupal7/sites/ssgb/site/sites/all/themes/sasson/phamlp/sass/tree/SassContext.php).

$body-text is the first variable found in my .scss file, so I guess the Compass compiler is falling over?

Is this expected? Shouldn't it deal with incorrect syntax better?