added error message if appointment add fails

smash/web/views/appointment.py

@@ -58,8 +58,7 @@ def appointment_add(request, visit_id=None):
             else:
                 return redirect('web.views.visit_details', id=visit_id)
         else:
-            raise ValidationError("Invalid request: Errors: {}. Non field errors: {}".format(form.errors, form.non_field_errors()))
-
+            messages.add_message(request, messages.ERROR, '{}'.format(form.non_field_errors()))
     else:
         form = AppointmentAddForm(user=request.user)