error message in irb

plist error

1.9.3-p194 :001 > require 'plist'
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:221: warning: else without rescue is useless
SyntaxError: /Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:216: syntax error, unexpected tLABEL
        when String, Symbol:          'string'
                            ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:217: syntax error, unexpected keyword_when, expecting keyword_end
        when Fixnum, Bignum, Integer: 'integer'
            ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:217: dynamic constant assignment
        when Fixnum, Bignum, Integer: 'integer'
                    ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:217: dynamic constant assignment
        when Fixnum, Bignum, Integer: 'integer'
                            ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:217: syntax error, unexpected tLABEL, expecting '='
        when Fixnum, Bignum, Integer: 'integer'
                                     ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:218: syntax error, unexpected keyword_when, expecting keyword_end
        when Float:                   'real'
            ^
/Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist/generator.rb:225: syntax error, unexpected keyword_end, expecting $end
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from /Users/sebastian/.rvm/gems/ruby-1.9.3-p194/gems/plist-3.1.7/lib/plist.rb:17:in `<top (required)>'
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
	from (irb):1
	from /Users/sebastian/.rvm/rubies/ruby-1.9.3-p194/bin/irb:16:in `<main>'