src/Pure/Tools/dump.scala

 
     if (theories_result.ok) session_result
     else {
       for {
         (name, status) <- theories_result.nodes if !status.ok
-        (tree, pos) <- theories_result.snapshot(name).messages if Protocol.is_error(tree)
+        (tree, _) <- theories_result.snapshot(name).messages if Protocol.is_error(tree)
       } progress.echo_error_message(XML.content(Pretty.formatted(List(tree))))
 
       session_result.copy(rc = session_result.rc max 1)
     }
   }