Rails Cannot call method 'charAt' of undefined

I have a Rails app getting the following error:

Less::ParseError in Home#index

Showing /Users/burtondav/sites/requestsys/app/views/layouts/application.html.erb where line #20 raised:

Cannot call method 'charAt' of undefined
  (in /Users/burtondav/sites/requestsys/app/assets/stylesheets/bootstrap_and_overrides.css.less)
Extracted source (around line #20):

17:       }
18:   </style>
19: 
20:   <%= stylesheet_link_tag "application", :media => "all" %>

Some GEMS I'm using:

gem 'rails', '3.2.11'
gem 'twitter-bootstrap-rails'
group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'
  gem 'less-rails'
  gem 'commonjs'
  gem 'therubyracer', :platforms => :ruby
  gem 'uglifier', '>= 1.0.3'

end

It seems to be a problem with LESS that Bootstrap uses.

I've read several other similar issues. So, I upgraded Ruby to 1.9.3p374. But, that didn't fix the problem.

Any ideas?

THANKS!

UPDATE

This is the bootstrap_and_overrides.css.less

@import "twitter/bootstrap/bootstrap";
@import "twitter/bootstrap/responsive";

// Set the correct sprite paths
@iconSpritePath: asset-path("twitter/bootstrap/glyphicons-halflings");
@iconWhiteSpritePath: asset-path("twitter/bootstrap/glyphicons-halflings-white");