Luabridge not working without "luaL_openlibs(L)"

Question

I cannot use luabridge without having the following line:

luaL_openlibs(lState);

And I don't even use its library functions.

I get this error :

Assertion failed: lua_istable (L, -1)

Just my adding "luaL_openlibs(lState)", no problems occur, but I don't want to use lua's libraries and want to make sure that they are not included.

My main function:

lua_State* lState = luaL_newstate();
    //luaL_openlibs(lState);
    getGlobalNamespace(lState).addFunction("log", print).beginNamespace("math").addFunction("sin", &std::sinf);

    luaL_dofile(lState, "res/script.lua");

    LuaRef start = getGlobal(lState, "start"); 

    try {
        start();
    } catch (const LuaException& e) {
        std::cout << e.what();
    }

    lua_close(lState);
    std::cin.get();