Ok, so I have made a mod called "skybox", and in it is "init.lua" and "textures". In the textures folder is "skybox_day.png" and "skybox_night.png".

The code I am using is this:

minetest.register_on_joinplayer(function(player)
    minetest.after(0, function()
        textures ={
        "skybox_day.png",
        "skybox_night.png",
        }

        player:set_sky({r=0, g=0, b=0, a=0},"skybox", textures)
    end)
end

And I get this error:

12:52:27: ERROR[main]: ========== ERROR FROM LUA ===========
12:52:27: ERROR[main]: Failed to load and run script from
12:52:27: ERROR[main]: C:\Users\Rhys\Documents\minetest-0.4.9-3rdpv2\bin\..\games\minetest_game\mods\skybox\init.lua:
12:52:27: ERROR[main]: ...9-3rdpv2\bin\..\games\minetest_game\mods\skybox\init.lua:10: ')' expected (to close '(' at line 1) near '<eof>'
12:52:27: ERROR[main]: ======= END OF ERROR FROM LUA ========
12:52:27: ERROR[main]: Server: Failed to load and run C:\Users\Rhys\Documents\minetest-0.4.9-3rdpv2\bin\..\games\minetest_game\mods\skybox\init.lua
12:52:27: ERROR[main]: ModError: ModError: Failed to load and run C:\Users\Rhys\Documents\minetest-0.4.9-3rdpv2\bin\..\games\minetest_game\mods\skybox\init.lua

What am I doing wrong?