Realms can crash with no internet connection

Relates to: MC-75722

I cannot completely reproduce, but I think the crash happened because I closed the internet connection while it was looking if it can reach the realms server after I pressed "Buy a realm".

I got also these error messages:

[18:12:19] [pool-5-thread-2/ERROR]: Couldn't get server list
com.mojang.realmsclient.exception.RealmsServiceException: Could not connect to Realms: mcoapi.minecraft.net
	at com.mojang.realmsclient.client.RealmsClient.execute(RealmsClient.java:399) ~[realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.client.RealmsClient.listWorlds(RealmsClient.java:98) ~[realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.gui.RealmsDataFetcher$ServerListUpdateTask.updateServersList(RealmsDataFetcher.java:142) [realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.gui.RealmsDataFetcher$ServerListUpdateTask.run(RealmsDataFetcher.java:134) [realms-1.7.7-pre2.jar:1.7.7-pre2]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_25]
	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [?:1.8.0_25]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_25]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:1.8.0_25]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_25]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_25]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
[18:12:19] [pool-5-thread-3/ERROR]: Couldn't get pending invite count
com.mojang.realmsclient.exception.RealmsServiceException: Could not connect to Realms: mcoapi.minecraft.net
	at com.mojang.realmsclient.client.RealmsClient.execute(RealmsClient.java:399) ~[realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.client.RealmsClient.pendingInvitesCount(RealmsClient.java:296) ~[realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.gui.RealmsDataFetcher$PendingInviteUpdateTask.updatePendingInvites(RealmsDataFetcher.java:176) [realms-1.7.7-pre2.jar:1.7.7-pre2]
	at com.mojang.realmsclient.gui.RealmsDataFetcher$PendingInviteUpdateTask.run(RealmsDataFetcher.java:168) [realms-1.7.7-pre2.jar:1.7.7-pre2]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_25]
	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [?:1.8.0_25]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_25]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:1.8.0_25]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_25]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_25]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]

Crash (1.8.2-pre4)

---- Minecraft Crash Report ----
// Everything's going to plan. No, really, that was supposed to happen.

Time: 18.01.15 18:07
Description: Rendering screen

java.lang.NullPointerException: Rendering screen
	at bxf.b_(SourceFile:437)
	at bvs.b_(SourceFile:83)
	at bxf.c(SourceFile:433)
	at bvs.c(SourceFile:73)
	at net.minecraft.realms.RealmsScreen.renderBackground(SourceFile:77)
	at com.mojang.realmsclient.gui.screens.RealmsGenericErrorScreen.render(RealmsGenericErrorScreen.java:67)
	at bvs.a(SourceFile:88)
	at cjj.a(SourceFile:1029)
	at bst.au(SourceFile:912)
	at bst.a(SourceFile:321)
	at net.minecraft.client.main.Main.main(SourceFile:124)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at bxf.b_(SourceFile:437)
	at bvs.b_(SourceFile:83)
	at bxf.c(SourceFile:433)
	at bvs.c(SourceFile:73)
	at net.minecraft.realms.RealmsScreen.renderBackground(SourceFile:77)
	at com.mojang.realmsclient.gui.screens.RealmsGenericErrorScreen.render(RealmsGenericErrorScreen.java:67)
	at bvs.a(SourceFile:88)

-- Screen render details --
Details:
	Screen name: bvs
	Mouse location: Scaled: (93, 208). Absolute: (186, 63)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2
Stacktrace:
	at cjj.a(SourceFile:1029)
	at bst.au(SourceFile:912)
	at bst.a(SourceFile:321)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 1.8.2-pre4
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 153740752 bytes (146 MB) / 230539264 bytes (219 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.8.2-pre4
	LWJGL: 2.9.1
	OpenGL: AMD Radeon HD 6800 Series GL version 4.4.13283 Compatibility Profile Context 14.501.1003.0, ATI Technologies Inc.
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: No
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: Deutsch (Deutschland)
	Profiler Position: N/A (disabled)