Fixed some potential sources of errors.

This was SVN commit r4539.

source/lib/res/sound/snd_mgr.cpp

@@ -1686,6 +1686,7 @@ Handle snd_open(const char* snd_fn, bool is_stream)
  */
 LibError snd_free(Handle& hvs)
 {
+	if(!hvs) return INFO::OK;
 	return h_free(hvs, H_VSrc);
 }
 

source/simulation/Entity.cpp

@@ -757,8 +757,9 @@ int CEntity::DestroyNotifier( CEntity* target )
 	std::vector<CEntity*>::iterator newEnd2 = std::remove_if(
 		m_notifiers.begin(), m_notifiers.end(),
 		bind2nd(std::equal_to<CEntity*>(), target));
-	int removed = std::distance(newEnd2, m_notifiers.end());
-	m_notifiers.erase(newEnd2, m_notifiers.end());
+	int removed = m_notifiers.end() - newEnd2;
+	//m_notifiers.erase(newEnd2, m_notifiers.end());
+	m_notifiers.resize(m_notifiers.size() - removed);
 	return removed;
 }
 void CEntity::DestroyAllNotifiers()
@@ -766,7 +767,7 @@ void CEntity::DestroyAllNotifiers()
 	debug_assert(entf_get(ENTF_DESTROY_NOTIFIERS));
 	//Make them stop listening to us
 	while ( ! m_notifiers.empty() )
-		DestroyNotifier( m_notifiers[0] );
+		DestroyNotifier( m_notifiers[m_notifiers.size()-1] );
 }
 CEntityFormation* CEntity::GetFormation()
 {

source/simulation/EntityManager.cpp

@@ -191,6 +191,7 @@ void CEntityManager::GetInRange( float x, float z, float radius, std::vector<CEn
 			for( size_t i=0; i<vec.size(); i++ )
 			{
 				CEntity* e = vec[i];
+				debug_assert(e != 0);
 				float dx = x - e->m_position.X;
 				float dz = z - e->m_position.Z;
 				if( dx*dx + dz*dz <= radiusSq )

source/sound/JSI_Sound.cpp

@@ -118,7 +118,8 @@ bool JSI_Sound::Loop( JSContext* UNUSED(cx), uintN UNUSED(argc), jsval* UNUSED(a
 // sounds are freed automatically when done playing.
 bool JSI_Sound::Free( JSContext* UNUSED(cx), uintN UNUSED(argc), jsval* UNUSED(argv) )
 {
-	snd_free(m_Handle);	// resets it to 0
+	if(m_Handle)
+		snd_free(m_Handle);	// resets it to 0
 	return true;
 }