sys_error;

--- a/src/Pure/Isar/locale.ML	Thu Jul 14 19:28:33 2005 +0200
+++ b/src/Pure/Isar/locale.ML	Thu Jul 14 19:28:34 2005 +0200
@@ -1983,7 +1983,7 @@
 
     val tinst = Symtab.make (map
                 (fn ((x, 0), T) => (x, T |> renameT)
-                  | ((_, n), _) => error "Internal error var in prep_registration") vinst);
+                  | ((_, n), _) => sys_error "Internal error var in prep_registration") vinst);
     val inst = Symtab.make (given_ps ~~ map rename vs);
 
     (* defined params without user input *)

--- a/src/Pure/Isar/proof_context.ML	Thu Jul 14 19:28:33 2005 +0200
+++ b/src/Pure/Isar/proof_context.ML	Thu Jul 14 19:28:34 2005 +0200
@@ -723,7 +723,7 @@
     fn th =>
       (case Seq.pull (exp th) of
         SOME (th', _) => th' |> Drule.local_standard
-      | NONE => raise CONTEXT ("Internal failure while exporting theorem", inner))
+      | NONE => sys_error "Failed to export theorem")
   end;
 
 val export_standard = gen_export_std export_view;