Lua how to push variables from lua to C++

Question

Hi I am trying to push variables from Lua to a C function, how would I do that? I have generated a C++ object on Lua side but want to send a number to that the objects function. But I get: Error when loading script with following string:

player.lua:2: attempt to index a function value (local 'myPlayer')

player.lua

local myPlayer = Player.new(69) 
myPlayer.testing(myPlayer, 24069) 

player.cpp

int player_test_pos(lua_State* L)
{
    player* myPlayer = l_CheckPlayer(L, 1);
    myPlayer->setPos({ 10, 0, 30 });
    int ok = lua_istable(L, 1);
    std::cout << ok << std::endl;
    ok = lua_isnumber(L, 2);
    std::cout << ok << std::endl;
    return 0;
}