(svn r12914) -Fix: Game crash when a spectator/server tried to show an engine with no owner when a NewGRF requested a specific variable.

src/newgrf_engine.cpp

@@ -478,6 +478,7 @@ static uint8 LiveryHelper(EngineID engine, const Vehicle *v)
 	const Livery *l;
 
 	if (v == NULL) {
+		if (!IsValidPlayer(_current_player)) return 0;
 		l = GetEngineLivery(engine, _current_player, INVALID_ENGINE, NULL);
 	} else if (v->type == VEH_TRAIN) {
 		l = GetEngineLivery((v->u.rail.first_engine != INVALID_ENGINE && (IsArticulatedPart(v) || UsesWagonOverride(v))) ? v->u.rail.first_engine : v->engine_type, v->owner, v->u.rail.first_engine, v);