[yavgui] Catch exceptions when creating transitions.

* yavgui/src/g_vcsn_handler_internal.hxx: Do that.

ChangeLog

+2009-08-10  d-halluin  <d-halluin@lrde.epita.fr>
+
+	[yavgui] Catch exceptions when creating transitions.
+
+	* yavgui/src/g_vcsn_handler_internal.hxx: Do that.
+
 2009-08-10  d-halluin  <d-halluin@lrde.epita.fr>
 	[yavgui] Improve transition creation.

yavgui/src/g_vcsn_handler_internal.hxx

@@ -236,6 +236,12 @@ namespace gui
     {
       using namespace vcsn::boolean_automaton;
 
+      std::stringstream str;
+      htransition_t i;
+
+      try
+      {
+
       // FIXME: Only for labels_are_series.
       series_set_t s = automaton.series();
       series_set_elt_t se = make_rat_exp(s.monoid().alphabet(),
@@ -243,11 +249,17 @@ namespace gui
 					 *(s.monoid().representation()),
 					 *(s.representation()));
 
-      htransition_t i = automaton.add_series_transition(src->index(),
+      i = automaton.add_series_transition(src->index(),
 					  dst->index(),
 					  se);
+      }
+      catch (std::exception& e)
+      {
+	QMessageBox::critical(NULL, "Exception occured",
+			      e.what ());
+	return;
+      }
 
-      std::stringstream str;
       str << automaton.series_of(i);
 
       GTransition* t = new GTransition(i, *src, *dst,