Don't app.init when document.body is null

assets/javascripts/application.js.coffee

@@ -20,6 +20,10 @@
 
 init = ->
   document.removeEventListener 'DOMContentLoaded', init, false
-  app.init()
+
+  if document.body
+    app.init()
+  else
+    setTimeout(init, 42)
 
 document.addEventListener 'DOMContentLoaded', init, false