Pressing realms button crashes the game

Whenever I click on the minecraft realms option in the menu screen, It  says 'saving world' and then the game suddenly crashes. It has happened to me 3 times today.

18w45a\: [^crash-2018-11-09_23.55.47-client.txt]

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 11/9/18 11:55 PM
Description: Rendering screen

java.lang.NoClassDefFoundError: net/minecraft/client/renderer/system/GlStateManager
	at com.mojang.realmsclient.RealmsMainScreen.drawRealmsLogo(RealmsMainScreen.java:880)
	at com.mojang.realmsclient.RealmsMainScreen.render(RealmsMainScreen.java:816)
	at coy.a(SourceFile:102)
	at dab.a(SourceFile:794)
	at clx.d(SourceFile:850)
	at clx.b(SourceFile:389)
	at net.minecraft.client.main.Main.main(SourceFile:145)
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.renderer.system.GlStateManager
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 7 more


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

-- Head --
Thread: Client thread
Stacktrace:
	at com.mojang.realmsclient.RealmsMainScreen.drawRealmsLogo(RealmsMainScreen.java:880)
	at com.mojang.realmsclient.RealmsMainScreen.render(RealmsMainScreen.java:816)
	at coy.a(SourceFile:102)

-- Screen render details --
Details:
	Screen name: coy
	Mouse location: Scaled: (206, 157). Absolute: (413.000000, 315.000000)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2.000000
Stacktrace:
	at dab.a(SourceFile:794)
	at clx.d(SourceFile:850)
	at clx.b(SourceFile:389)
	at net.minecraft.client.main.Main.main(SourceFile:145)

-- System Details --
Details:
	Minecraft Version: 18w45a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 680451552 bytes (648 MB) / 1060372480 bytes (1011 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 7 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	Launched Version: 18w45a
	LWJGL: 3.1.6 build 14
	OpenGL: GeForce 210/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	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: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: vanilla, file/Low Shield & Fire, file/Dark Mode
	Current Language: English (US)
	CPU: 6x AMD Phenom(tm) II X6 1045T Processor