Lanterns pointlessly render their outer faces on the inside

The bug

The outer faces of lanterns (both on the ground and hanging) are also rendered on the inside, despite the fact that it's normally not possible to be inside of lanterns, and so these faces go largely unseen.

How to reproduce

1. Place a lantern
2. Enter Spectator mode
3. Fly into the lantern

Expected results

When inside the lantern, you should be able to see outside of it as if the lantern wasn't there.

Actual results

You can't, as the outer faces of the lantern are in the way.