* spot/twa/twa.cc: Typo.

spot/twa/twa.cc

@@ -85,7 +85,7 @@ namespace spot
   {
     if (acc().uses_fin_acceptance())
       throw std::runtime_error("twa::accepting_run() does not work with "
-                               "Fin acceptance (but twa:is_empty() and "
+                               "Fin acceptance (but twa::is_empty() and "
                                "twa::accepting_word() can)");
     auto res = couvreur99_new_check(shared_from_this());
     if (!res)