make sure entries are actually erased :-)

diff --git a/src/Scripting/NasalSys.cxx b/src/Scripting/NasalSys.cxx
index 9e4a75ad1a8d3cc238b9951d85e13c75a8b6ae94..f4d6a5db3aa47608628ae8a0880ab58bf72957fc 100644 (file)
--- a/src/Scripting/NasalSys.cxx
+++ b/src/Scripting/NasalSys.cxx
@@ -434,13 +434,11 @@ void FGNasalSys::update(double)
     if(_purgeListeners) {
         _purgeListeners = false;
         map<int, FGNasalListener *>::iterator it;
-        for(it = _listener.end(); it != _listener.end();) {
+        for(it = _listener.end(); --it != _listener.end();) {
             FGNasalListener *nl = it->second;
             if(nl->_dead) {
-                _listener.erase(it--);
+                _listener.erase(it);
                 delete nl;
-            } else {
-              --it;
             }
         }
     }