Realms: "[Client thread/FATAL]: Error executing task"

When connecting with 1.8.2-pre3 to Realms, the game console gets spammed with

[20:17:20] [Client thread/INFO]: Setting user: Kumasasa
[20:17:20] [Client thread/INFO]: (Session ID is token:38a38c5cd93a4f3eb7fbb978a2b3f320:212c6adb6aad4b04ab210d52a98931c0)
[20:17:22] [Client thread/INFO]: LWJGL Version: 2.9.1
[20:17:25] [Client thread/INFO]: Reloading ResourceManager: Default, Misa Patch Les 1.8.zip, Misa.zip, XDBMisaPatchV1.4.zip
[20:17:25] [Client thread/WARN]: ResourcePack: ignored non-lowercase namespace: %s in %s
[20:17:27] [Sound Library Loader/INFO]: Starting up SoundSystem...
[20:17:27] [Thread-6/INFO]: Initializing LWJGL OpenAL
[20:17:27] [Thread-6/INFO]: (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
[20:17:27] [Thread-6/INFO]: OpenAL initialized.
[20:17:27] [Sound Library Loader/INFO]: Sound engine started
[20:18:04] [Client thread/INFO]: Created: 2048x2048 textures-atlas
[20:23:35] [Client thread/INFO]: Realms library version == 1.7.7-pre
[20:23:38] [MCO Availability Checker #1/INFO]: Realms is available for this user
[20:26:10] [Client thread/INFO]: [CHAT] <Kumasasa> testing 1.8.2-pre3
[20:26:42] [Client thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
	at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_25]
	at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_25]
	at w.a(SourceFile:45) [1.8.2-pre3.jar:?]
	at bst.at(SourceFile:878) [1.8.2-pre3.jar:?]
	at bst.a(SourceFile:321) [1.8.2-pre3.jar:?]
	at net.minecraft.client.main.Main.main(SourceFile:124) [1.8.2-pre3.jar:?]
Caused by: java.lang.NullPointerException