Getting an error in Johnson's env.js

Hi,
I am trying to use Johnson gem to run javascript without a browser. But
the env.js gives me an exception which looks like this

/var/lib/gems/1.8/gems/johnson-1.1.0/lib/johnson/spidermonkey/runtime.rb:58:in
native_compile': illegal character at (none):12 (Johnson::Error) from /var/lib/gems/1.8/gems/johnson-1.1.0/lib/johnson/spidermonkey/runtime.rb:58:incompile’
from
/var/lib/gems/1.8/gems/johnson-1.1.0/lib/johnson/spidermonkey/runtime.rb:42:in
evaluate' from /var/lib/gems/1.8/gems/johnson-1.1.0/lib/johnson/runtime.rb:21:inevaluate’
from test1.rb:802
from
/var/lib/gems/1.8/gems/nokogiri-1.2.3/lib/nokogiri/xml/node_set.rb:140:in
each' from /var/lib/gems/1.8/gems/nokogiri-1.2.3/lib/nokogiri/xml/node_set.rb:139:inupto’
from
/var/lib/gems/1.8/gems/nokogiri-1.2.3/lib/nokogiri/xml/node_set.rb:139:in
each' from /var/lib/gems/1.8/gems/taka-0.0.1/lib/taka/dom/node_list.rb:9:insend’
from /var/lib/gems/1.8/gems/taka-0.0.1/lib/taka/dom/node_list.rb:9:in
`method_missing’
from test1.rb:800

Any idea on whats wrong here?