iro.show.backtrace.patch

diff --git a/autoload/iro/ruby.vim.rb b/autoload/iro/ruby.vim.rb
index 9bb1d7b..a638d01 100644
--- a/autoload/iro/ruby.vim.rb
+++ b/autoload/iro/ruby.vim.rb
@@ -11,6 +11,9 @@ module IroVim
       source = Vim.evaluate("getbufline(#{bufnr}, 1, '$')").join("\n")
       result = Iro::Ruby::Parser.tokens(source)
       Vim.command 'let s:result = ' + JSON.generate(result)
+    rescue => ex
+      puts ex.backtrace
+      raise
     end
   end
 end