antiq: preview errors;

--- a/src/Pure/Isar/isar_output.ML	Sat Dec 23 22:53:05 2000 +0100
+++ b/src/Pure/Isar/isar_output.ML	Sat Dec 23 22:53:27 2000 +0100
@@ -141,6 +141,7 @@
     fun expand (Antiquote.Text s) = s
       | expand (Antiquote.Antiq x) =
           let val (opts, src) = antiq_args lex x in
+            options opts (fn () => command src state) ();  (*preview errors!*)
             Library.setmp print_mode (Latex.modes @ ! print_mode)
               (options opts (fn () => command src state)) ()
           end;