Update

after/syntax/help.vim

@@ -1,6 +1,12 @@
-let b:current_syntax = ''
-unlet b:current_syntax
+" Extends standard help syntax with highlighting of Scala code.
+"
+" Place code between !sc! and !/sc! delimiters. These will be hidden if Vim is
+" built with conceal support.
+
+unlet! b:current_syntax
+
 syntax include @ScalaCode syntax/scala.vim
+
 if has('conceal')
   syntax region rgnScala matchgroup=Ignore concealends start='!sc!' end='!/sc!' contains=@ScalaCode
 else