Digging finding space rather than lava

When digging one should find the inner part of a planet which is made of lave. However in Minecraft after digging so deep one will find stars and space (refer attachment) . This is incorrect.

If one is working in creative mode one should find lava and he or she is able to progress with digging the gamer should end up on the other side of the planet, getting out of lava and then digging rock.

Appreciate if you could fix it.

Thanks