public void SetMetatable(int idx)
{
var val = stack.get(idx);
var mtVal = stack.pop();
if (mtVal == null)
{
LuaValue.setMetatable(val, null, this);
}
else if (mtVal is LuaTable mtl)
{
LuaValue.setMetatable(val, mtl, this);
}
else
{
throw new Exception("table expected!"); // todo
}
}