The game crashed whilst rendering screen Error: java.lang.NullPointerException: Rendering screen

After launching Java Edition 1.6 I clicked on Minecraft Realms, only to be met with an empty page with nothing but the "Minecraft Realms" title at the top. After waiting for a couple of minutes Minecraft crashes and I get an error saying: "The game crashed whilst rendering screen Error: java.lang.NullPointerException: Rendering screen"

I've tried multiple times to open realms. I tried restarting the game, restarting my computer, and even deleting and reinstalling the game. What is going on?