Crashes while opening realms.

crash report won't upload.

---- Minecraft Crash Report ----
// Why is it breaking

Time: 11/2/18, 12:07 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 cop.a(SourceFile:102)
at czs.a(SourceFile:793)
at clp.d(SourceFile:850)
at clp.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.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
... 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 cop.a(SourceFile:102)

– Screen render details –
Details:
Screen name: cop
Mouse location: Scaled: (267, 171). Absolute: (535.000000, 343.000000)
Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2.000000
Stacktrace:
at czs.a(SourceFile:793)
at clp.d(SourceFile:850)
at clp.b(SourceFile:389)
at net.minecraft.client.main.Main.main(SourceFile:145)

– System Details –
Details:
Minecraft Version: 18w44a
Operating System: Linux (amd64) version 4.15.0-38-generic
Java Version: 10.0.2, Oracle Corporation
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 652171984 bytes (621 MB) / 1342177280 bytes (1280 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
Launched Version: 18w44a
LWJGL: 3.1.6 build 14
OpenGL: AMD CARRIZO (DRM 3.23.0 / 4.15.0-38-generic, LLVM 6.0.0) GL version 3.0 Mesa 18.0.5, X.Org
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
Current Language: English (US)
CPU: 4x AMD A12-9800 RADEON R7, 12 COMPUTE CORES 4C+8G