Lua API: Fix crash if passing an out-of-bounds side to wesnoth.interf…

…ace.end_turn

src/scripting/game_lua_kernel.cpp

@@ -1671,7 +1671,7 @@ int game_lua_kernel::intf_end_turn(lua_State* L)
 	//but the later will make the turn counter change aswell fire turn end events accoringly etc.
 	if (!lua_isnoneornil(L, 1)) {
 		int npn = luaL_checkinteger(L, 1);
-		if (npn <= 0 /*TODO: || npn > 2*nteams*/) {
+		if (npn <= 0  || npn > 2 * teams().size()) {
 			return luaL_argerror(L, 1, "side number out of range");
 		}
 		resources::controller->gamestate().next_player_number_ = npn;